JPH0369966A - Electrostatic latent image developing toner and manufacture of master batch for the same - Google Patents

Abstract

PURPOSE:To disperse a dye or pigment finely and uniformly into a binder resin by dissolving the resin in a solvent, on the other hand, pulverizing and dispersing the dye or pigment in a solvent, mixing the resin solution with the dye or pigment dispersion, and then, removing the solvents. CONSTITUTION:The binder resin, such as polystyrene, on a copolymer of styrene and acrylate, like butyl acrylate, on styrene and methacrylate like butyl methacrylate, is used, and this resin is dissolved in the organic solvent to prepare the resin solution, on the other hand, the dye or pigment is pulverized and dispersed in the organic solvent having polar groups in the molecule to prepare the dye or pigment dispersion, this solution and this dispersion are mixed and the solvents are removed, thus permitting the obtained toner particles to contain the dye or pigment finely and uniformly dispersed in them.

Description

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

Conventionally, as a distortion 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 too 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, and the developing This may contaminate the area around the machine, or during the development process, toner may adhere to areas other than the image on the photoreceptor, 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, toners used for electrophotography, electrostatic printing, etc. are 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 heating kneader. -1 Melt kneading using means such as heating 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 masterbatch is melt-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 the dye and pigment finely and uniformly in the liquid.Furthermore, in cases where a masterbatch is not used, dyes and pigments are sometimes used in larger amounts than necessary; This method does not essentially solve the above-mentioned problems, and since dyes and pigments are generally expensive, it unnecessarily increases the cost of producing 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 above-mentioned various problems in conventional toner production, and it uses toner particles in which dyes and pigments are finely and uniformly dispersed in each toner particle. It is an object of the present invention to provide a manufacturing method and a method for manufacturing a masterbatch that can be suitably used for manufacturing such toner.

According to the present invention, (a) dissolving the binder resin in an organic solvent to prepare a resin solution; (b) pulverizing the dye and pigment in the organic solvent; Provided is a method for producing a masterbatch, comprising the steps of: (c) mixing the resin solution and the dye and pigment dispersion, and then removing the solvent. .

Further, according to the present invention, (a) dissolving the binder resin in an organic solvent to prepare a resin solution; (b) pulverizing and dispersing the dye and pigment in the organic solvent to disperse the dye and pigment; (c) After mixing the resin solution and the dye/pigment dispersion, the solvent is removed to obtain a masterbatch; (d) The masterbatch is further mixed with a binder resin as necessary. An electrostatic latent image characterized by comprising a step of adding a characteristic imparting agent and kneading to produce a kneaded product, and (e) a step of crushing the kneaded product to a required particle size to obtain a toner. A method of manufacturing a developing toner is provided.

In the present invention, the binder resin includes any resin conventionally used in toners, such as styrene, O
-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, diethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylonide 1
nor, methacrylonitrile, acrylamide, glycidyl acrylate, glycidyl methacrylate, acrylic acid,
Examples include (co)polymers of one or more radically polymerizable monomers such as methacrylic acid, 2-vinylpyridine, and 4-vinylpyridine.

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.

Further, as the dye/pigment, for example, any powder or granular dye/pigment that is 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, for example, the following formula (X- represents an anion species): Nigrosine dyes, including electron-donating dyes such as the nigrosine dyes shown below, (wherein X' represents a cationic species), or (wherein X' represents a cationic species) (' Subiron Black TRH, (manufactured by Hodogaya Chemical Industry ■)
Examples include electron-accepting dyes such as metal complex salts of monoazo dyes shown in the following.

-i, 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 binder resin is dissolved in an organic solvent to prepare a resin solution, and a dye and pigment is separately ground and dispersed in an organic solvent to prepare a dye and pigment dispersion. , After mixing these resin solutions and the dye and pigment dispersion,
By removing the solvent, a masterbatch in which the dye and pigment are finely and uniformly dispersed in the binder resin can be obtained.

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, and alcohols such as propanol and butanol are preferably used.

Moreover, mixed solvents of these are also suitably used. but,
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.

On the other hand, the organic solvent used to prepare the dye and pigment dispersion is one that sufficiently wets the dye and pigment used, and is preferably the same as the solvent used to prepare the resin solution. However, solvents different from those for preparing the resin solution can also be used. In this case, it is necessary that the solvent dissolves the resin when the obtained dye/pigment dispersion and resin solution are mixed.

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 fi parts 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.

In preparing the dye and pigment dispersion, 1 to 40 parts by weight, preferably 5 to 20 parts by weight of the dye and pigment are used per 100 parts by weight of the solvent. Further, as a means for pulverizing and dispersing the dye and pigment in a solvent, for example, an ordinary wet pulverizer such as a ball mill or an annular wet pulverizer can be used.

In preparing the dye and pigment dispersion, a dye and pigment dispersion stabilizer can be used. As such a dispersion stabilizer, for example, ethylene-vinyl acetate copolymer or the like is suitably used. Furthermore, a polymer having a lower interfacial tension with water than the resin used can also be used. Thus, when using a dispersion stabilizer, a low polarity solvent is suitable.

According to the present invention, a masterbatch in which the dye and pigment are dispersed is prepared by mixing the resin solution prepared as described above and the dye and pigment dispersion, and removing the solvent from the mixture. Here, for 100 parts by weight of the resin solution, the amount of the dye and pigment dispersion is 500 parts by weight.
It is mixed in an amount of not more than 200 parts by weight, preferably not more than 200 parts by weight. The solvent can be removed by general methods such as drying the mixture by heating, drying under reduced pressure, and freeze-drying.

If necessary, the masterbatch may be crushed or crushed.

In this way, a resin composition in which the dye and pigment are uniformly and finely dispersed in the binder resin can be obtained as a masterbatch. According to the method of the present invention, the dye and pigment are initially
Even if the toner contains particles larger than the target toner particle size, they are finely and uniformly dispersed in the binder resin.

That is, the dye and pigment usually have a diameter of about 5 μm or less, preferably,
It is uniformly dispersed in the resin with a particle size of about 1 μm.

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 kneaded product 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 used in an amount of 30 to 300 parts by weight, preferably 30 to 100 parts by weight, based on 100 parts by weight of the binder resin.

In step (d) above, a binder resin and, if necessary, a characteristic imparting agent are further added to the masterbatch and kneaded using a conventional kneading means such as a roll, kneader, Banbury roll, or extruder. be able to.

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 separately, the dye and pigment are pulverized and dispersed in the solvent, and then the resin solution and the dye and pigment are mixed. The dye and pigment are dispersed in the resin by mixing with the dye and pigment dispersion and replacing the solvent in the dye and pigment dispersion with the resin, thereby obtaining a masterbatch in which the dye and pigment are finely and uniformly dispersed in the resin. I can do it.

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 filling, 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 0.5 parts by weight of a monoazo chromium dye (Spiron Black TRH manufactured by Hodogaya Chemical Industry Co., Ltd.) as a charge control agent and ethylene-vinyl acetate copolymer (Soabrene manufactured by Nippon Gosei Chemical Industry Co., Ltd.) as a dispersion stabilizer 0.2 parts by weight of CH) was added to 5 parts by weight of toluene, and the dye was ground in a ball mill for 50 hours.

Separately, a styrene-acrylic acid ester copolymer (Himer TB-1000 manufactured by Sanyo Kagyo Co., Ltd.) was used as a binder resin.
1 part by weight was dissolved in 5 parts by weight of toluene to obtain a resin solution.

Next, the dye dispersion liquid was added to this resin solution and mixed with stirring, and then the 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, 1.7 parts by weight of this masterbatch and 98.81 parts of the same styrene-acrylic acid ester copolymer as above were added.
1 part, 3 parts by weight of low molecular weight polypropylene (Viscol 550P manufactured by Sanyo Chemical Industries Ltd.) as an anti-offset imparting agent, and 1 part by weight of carbon black (MA-8 manufactured by Mitsubishi Chemical Corporation Ltd.)
031iit parts were mixed, melt-kneaded using a twin-screw extruder, and then 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.

Next, 0.3 parts by weight of silicic acid fine powder (Aerosil R-972 manufactured by Nippon Aerosil ■) was mixed with 100 parts by weight of this toner, and this was further mixed with a carrier (Nippon Tetsuko Co., Ltd., Aerosil R-972) so that the toner concentration was 6% by weight. EFV250), to prepare a two-component developer.

This developer was used for electrostatic copying on commercially available plain paper M (manufactured by Sanyo Electric ■, 5F).
T-1102Z), 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 the invention, even after copying 10,000 sheets, clear and beautiful images without background stains could be stably obtained. Further, neither filming on the photoreceptor nor contamination inside the developing machine 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 3. Measurement is done by Hosokawa Micron ■
The measurement was carried out using a charge distribution measuring device manufactured by Manufacturer Co., Ltd. According to the developer according to the present invention, it is shown that the toner has a narrow charge distribution width and substantially does not contain an amount of oppositely charged toner.

Example 2 1 part by weight of the same monoazo chromium dye as in Example 1 and 0.4 parts by weight of ethylene-vinyl acetate copolymer were added to 10 parts by weight of toluene, and the dye was ground in a ball mill for 50 hours.

Separately, 2 parts by weight of the same styrene-acrylic ester copolymer as in Example 1 was dissolved in 20 parts by weight of toluene to obtain a resin solution.

Next, the dye dispersion was added to the resin solution and mixed with stirring, and then the mixture was heated under reduced pressure to remove the solvent, thereby obtaining a resin mass. This resin mass was pulverized to obtain a masterbatch containing a charge control agent.

Next, 3.4 parts by weight of this masterbatch, 97.6 parts by weight of the same styrene-acrylic acid ester copolymer as above, 3 parts by weight of low molecular weight polypropylene, and 10 parts by weight of carbon black were mixed and mixed in a twin screw extruder. After melt-kneading, the mixture was pulverized using a jet pulverizer. Next, the particles were classified using an air classifier to produce toner having a particle size of 5 to 20 μm three times.

Next, 0.3 parts by weight of silicic acid fine powder (Aerosil R-972 manufactured by Nippon Aerosil ■) was mixed with 100 parts by weight of this toner, and further, this was mixed to give a toner concentration of 6% by weight. EFV250), to prepare a two-component developer.

Using this developer, in the same manner as in Example 1, 1000
The images were evaluated by making 0 consecutive copies. The results are shown in Table 1. In addition, the relationship between the number of copies and image density is
As shown in the figure. According to the invention, even after copying 10,000 sheets, clear and beautiful images without background stains could be stably obtained. Further, neither filming on the photoreceptor nor contamination inside the developing machine 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 3. According to the toner of the present invention, it is shown that the charge distribution width is narrow and that there is substantially no amount of oppositely charged toner.

Example 3 1 part by weight of nigrosine dye (Nigrosine Base EX manufactured by Orient Kagaku Kogyo ■) as a charge control agent and 0.4 part by weight of the same ethylene-vinyl acetate copolymer as in Example 1 were added to 10 parts by weight of toluene. The dye was ground in a ball mill for 50 hours.

Separately, 2 parts by weight of the same styrene-acrylic ester copolymer as in Example 1 was dissolved in 20 parts by weight of toluene to obtain a resin solution.

Next, the dye dispersion liquid was added to this resin solution and mixed with stirring, and then the 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, 3.4 parts by weight of this masterbatch, 97.6 parts by weight of the same styrene-acrylic acid ester copolymer as above, 3 parts by weight of low molecular weight polypropylene, 1.5 parts by weight of carbon black, and 7 gnetite (manufactured by Toda Kogyo ■) were added. EPT-
500) 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, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 5 shows the relationship between the number of copies and image density. According to the present invention, even after copying 100 copies, clear and beautiful images without background stains could be obtained.

Further, neither filming on the photoreceptor nor contamination inside the developing machine was observed.

Further, as shown in FIG. 7, the triboelectric charge amount distribution of the developer prepared with a toner concentration of 5% by weight relative to the carrier is narrow, and the amount of reversely charged toner is also small.

Example 4 3 parts by weight of the same nigrosine dye as in Example 3 and 1.2 parts by weight of the same ethylene-vinyl acetate copolymer as in Example 1 were added to 30 parts by weight of toluene, and the dye was ground in a ball mill for 50 hours.

Separately, 6 parts by weight of the same styrene-acrylic acid ester copolymer as in Example 1 was dissolved in 60 parts by weight of toluene to obtain a resin solution.

Next, the dye dispersion was added to the resin solution and mixed with stirring, and then the 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, 10.2 parts by weight of this masterbatch, 92.8 parts by weight of the same styrene-acrylic acid ester copolymer as above, 3 parts by weight of low molecular weight polypropylene, 1.5 parts by weight of carbon black, and the same magnetite 60 as in Example 3 were added. Parts by weight were mixed, melt-kneaded using a twin-screw extruder, and then 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.

Using the obtained toner, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 5 shows the relationship between the number of copies and image density. According to the present invention, even after copying 10,000 sheets, clear and beautiful images without background stains could be obtained.

Further, neither filming on the photoreceptor nor contamination inside the developing machine was observed.

Further, as shown in FIG. 7, the triboelectric charge amount distribution of the developer prepared with a toner concentration of 5% by weight relative to the carrier is narrow, and the amount of reversely charged toner is also small.

Comparative Example 1 0.5 parts by weight of the same monoazo chromium dye as in Example 1, 100 parts by weight of ethylene-vinyl acetate copolymer, 3 parts by weight of low molecular weight polypropylene and 10 parts by weight of carbon black were mixed, and the mixture was placed in a twin-screw extruder. After melt-kneading, the mixture 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.

Next, 0.3 parts by weight of silicic acid fine powder (Aerosil R-972 manufactured by Nippon Aerosil ■) was mixed with 100 parts by weight of this toner, and further, this was mixed to give a toner concentration of 6% by weight. EFV250), to prepare a two-component developer.

Using the obtained 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 the present invention, the image density fluctuated and background fog was observed in the image.

Further, as shown in FIG. 4, the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier, the toner particles have a wide charge distribution width and
It is shown that oppositely charged particles are also present in significant amounts.

Comparative Example 2 A developer was prepared in the same manner as Comparative Example 1 except that 1 part by weight of monoazo chromium dye was used as a charge control agent.

Using the obtained developer, to
Continuous copying of 00 sheets was performed 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 the present invention, the image density fluctuated and background fog was observed in the image.

Further, as shown in FIG. 4, the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier, the toner particles have a wide charge distribution width and
It is shown that oppositely charged particles are also present in significant amounts.

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

Using the obtained 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 the present invention, the image density fluctuated and background fog was observed in the image.

Further, as shown in FIG. 4, the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier, the toner particles have a wide charge distribution width and
It is shown that oppositely charged particles are also present in significant amounts.

Comparative Example 4 1 part by weight of the same nigrosine dye as in Example 3, 100 parts by weight of the same styrene-acrylate copolymer as in Example 1, 3 parts by weight of low molecular weight polypropylene, 1.5 parts by weight of carbon black, and the same as in Example 3. 1 to 60 parts by weight of the same magnetite were mixed, melt-kneaded using a twin-screw extruder, and then 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.

Using the obtained developer, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 6 shows the relationship between the number of copies and image density. According to the present invention, the image density fluctuated and background fog was observed in the image.

Further, as shown in FIG. 8, the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier, the toner particles have a wide charge distribution width and
It is shown that oppositely charged particles are also present in significant amounts.

Comparative Example 5 A toner was prepared in the same manner as Comparative Example 4 except that 3 parts by weight of nigrosine dye was used as a charge control agent.

Using the obtained developer, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 6 shows the relationship between the number of copies and image density. According to the present invention, the image density fluctuated, background fog was observed in the image, and filming was observed on the photoreceptor.

Further, as shown in FIG. 8, the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier, the toner particles have a wide charge distribution width and
It is shown that oppositely charged particles are also present in significant amounts.

[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 friction band amount distribution of the toner obtained by the method of the present invention, FIG. 4 is a graph showing the triboelectric charge amount distribution of the toner as a comparative example, and FIG. A graph showing the relationship between the number of copies and image density when an image is copied using the developer obtained by the method,
FIG. 6 is a graph showing the relationship between the number of copies and image density when using a developer as a comparative example. FIG. 7 is a graph showing the triboelectric charge amount distribution of the toner obtained by the method of the present invention. FIG. 8 is a graph showing the triboelectric charge amount distribution of toner as a comparative example. Figure 3 Figure 4 Figure 1 Atsushi Ryōjin 1 ( Figure 2 Takehisae deception Figure 6 Figure 6 fPt″Hisashi 3 虻(x foθθ〕 (x fODO) (xfooO)

Claims (5)

[Claims] (1) (a) A step of dissolving a binder resin in an organic solvent to prepare a resin solution. (b) A step of grinding and dispersing the dye and pigment in an organic solvent to prepare a dye and pigment dispersion. (c) A method for producing a masterbatch, comprising the step of removing the solvent after mixing the resin solution and the dye/pigment dispersion. (2) In step (b), in the presence of a dispersion stabilizer,
2. The method for producing a masterbatch according to claim 1, wherein the dye and pigment are pulverized and dispersed in an organic solvent to prepare a dye and pigment dispersion. (3) (a) A step of dissolving the binder resin in an organic solvent to prepare a resin solution; (b) A step of pulverizing and dispersing the dye and pigment in an organic solvent to prepare a dye and pigment dispersion. (c) a step of mixing the resin solution and the dye/pigment dispersion and then removing the solvent to obtain a masterbatch; (d) further adding a binder resin and, if necessary, a characteristic imparting agent to the masterbatch; , kneading to produce a kneaded product; and (e) pulverizing the kneaded product to a required particle size to obtain a toner. . (4) In step (b), in the presence of a dispersion stabilizer,
4. The method for producing a toner for developing electrostatic latent images according to claim 3, wherein the dye and pigment are pulverized and dispersed in an organic solvent to prepare a dye and pigment dispersion. (5) 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 .