JPH03155567A - Production of toner for developing electrostatic latent image and production of dye and pigment dispersion used therefor - Google Patents

Abstract

PURPOSE:To finely and uniformly disperse dyes and pigments into individual toner particles by grinding and dispersing the dyes and pigments into a polymerizable monomer and polymerizing the polymerizable monomer and then removing the unreacted polymerizable monomer. CONSTITUTION:The dyes and pigments are ground and dispersed into the polymerizable monomer and after the polymerizable monomer is polymerized, the unreacted polymerizable monomer is removed. Ordinary wet process grinding mills, such as, for example, ball mills and annular type wet process grinding mills, are usable as the means of grinding and dispersing the dyes and pigments into the polymerizable monomer. The polymn. of the polymerizable monomer is executed by ordinary polymn. methods, such as bulk polymn., suspension polymn., and emulsion polymn., more particularly preferably by suspension polymn. or emulsion polymn. After the dyes and pigments are ground and dispersed in the polymerizable monomer, the monomer is polymerized and, therefore, the resin compsn. finely and uniformly dispersed with the dyes and pigments in the resin is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a dye and pigment dispersion resin and a method for producing a toner for developing electrostatic latent images using the dye and pigment dispersion resin.

Conventionally, in the old 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 an 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 due to 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,
Image characteristics are unstable, such as a decrease in image density, toner scattering, blurring, and unevenness of the image. 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 a darkening 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 in electrophotography, electrostatic printing, etc. are usually produced by mixing dyes and pigments 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 finely and uniformly in the liquid.

Furthermore, when a masterbatch is not used, dyes and pigments are sometimes used in larger amounts than necessary, but such methods do not essentially solve the above-mentioned problems, and -i In addition, dyes and pigments are expensive, which 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 a large amount of solvent is required to obtain a resin solution containing the required amount of charge control agent.
It is disadvantageous.

- The present invention was made in order to solve the above-mentioned seeding problem in conventional toner production, and the dye and pigment are finely and uniformly dispersed in each toner particle. It is an object of the present invention to provide a method for producing toner particles containing a mixture thereof, and a method for producing a dye-pigment dispersion resin as a masterbatch that can be suitably used for producing such a toner.

1. According to the present invention, the dye and pigment are first pulverized and dispersed in a polymerizable monomer, and then, after the polymerizable monomer is polymerized, unreacted polymerization is carried out. Provided is a method for producing a dye/pigment dispersion resin, which is characterized by removing the monomer.

Furthermore, according to the present invention, the dye and pigment are pulverized and dispersed in a polymerizable monomer, and then, after the polymerizable monomer is polymerized, unreacted polymerizable monomer is removed. to obtain a dye and pigment dispersion resin, and then add a binder resin and, if necessary, a property imparting agent to the above-mentioned dye and pigment dispersion resin, melt and knead it, and crush the obtained kneaded product, Provided is a method for producing a toner for developing an electrostatic latent image, which comprises classifying the toner.

In the present invention, the polymerizable monomer used for preparing the dye/pigment dispersion resin is particularly one that provides a (co)polymer that is compatible with the binder resin described below.
Although not limited to (any radically polymerizable monomer may be used, for example, styrene, (meth)acrylic acid, derivatives such as esters or amides thereof, maleic acid,
Maleic acid ester, vinyl acetate, etc. are preferably used. These monomers may be used alone or as a mixture of two or more. Of course, the monomers may be selected so as to provide the same resin as the binder resin described below.

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 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), and (wherein, X' represents a cationic species) ([ Spiron Black TRHJ (Hodogaya Chemical Industry Q)
Examples include electron-accepting dyes such as metal complex salts of monoazo dyes (manufactured by I).

According to the present invention, in the preparation of the dye and pigment dispersion resin, 0.1 to 50 parts of the dye and pigment are added to 100 parts by weight of the polymerizable monomer.
Parts by weight, preferably 0.5 to 20 parts by weight, are used.

Examples of means for pulverizing and dispersing dyes and pigments in polymerizable monomers include ball mills, annular wet mills, etc.
A conventional wet grinder can be used. Further, when pulverizing and dispersing the dye and pigment in the polymerizable monomer, 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, 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, after the dye and pigment are pulverized and dispersed in the polymerizable monomer, the polymerizable monomer is polymerized. Polymerization of polymerizable monomers includes bulk polymerization, suspension polymerization, emulsion polymerization, etc.
Although conventionally known polymerization methods can be used, suspension polymerization or emulsion polymerization is particularly preferred. Of course, polymerization initiators and additives are used depending on these polymerization methods.

After polymerization, unreacted monomers can be removed from the resulting polymerization mixture by conventional methods such as drying the mixture by heating, drying under reduced pressure, and freeze-drying. In this way, the dye and pigment dispersion resin according to the present invention can be obtained.

If necessary, the obtained dye and pigment dispersion resin may be pulverized or crushed.

Next, according to the present invention, a binder resin and, if necessary, a characteristic imparting agent are further added to the dye and pigment dispersion resin obtained as described above, and the mixture is kneaded to produce a kneaded product. Next, a toner can be obtained by pulverizing this kneaded material to a required particle size.

The binder resin may be the same as or different from the resin in the dye and pigment dispersion resin, but if different, it is desirable that it has good compatibility with the resin in the dye and pigment dispersion resin.

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, grindyl 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.

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 order to further add a binder resin and, if necessary, a characteristic imparting agent to the dye/pigment dispersion resin and knead them, a conventional kneading means such as a roll, a kneader, a Banbury roll, an extruder, etc. can be used.

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 grinding. 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. 20 In the 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, the dye and pigment are pulverized and dispersed in the polymerizable monomer, and then the monomer is polymerized, so that the dye and pigment are finely and uniformly dispersed in the resin. It is possible to obtain a resin composition dispersed in.

Furthermore, according to the present invention, if the dye and pigment dispersion resin is further kneaded with a binder resin and, if necessary, a property-imparting agent, and after cooling, the dye and pigment and property-imparting agent are mixed into the resin. It is possible to obtain toner finely and uniformly dispersed therein.

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 dyeing on the photoreceptor is prevented. There is no pigment adhesion, ie, 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 0.5 parts by weight of monoazo chromium dye (Spiron Black TRH manufactured by Hodogaya Chemical Industry Co., Ltd.) as a charge control agent and ethylene-vinyl acetate copolymer (Sorblen manufactured by Nippon Gosei Chemical Industry Co., Ltd.) as a dispersion stabilizer A dye-dispersed monomer composition was prepared by adding 0.2 parts by weight of CH) to 87 parts by weight of styrene and pulverizing the dye in a ball mill under a nitrogen atmosphere for 50 hours.

Separately, 0.6 parts by weight of partially saponified polyvinyl alcohol with a degree of saponification of 86.5 mol% and a degree of polymerization of 2300 (Gohsenol 0H-23 manufactured by Nippon Gosei Kagaku Kogyo) as a dispersant was dissolved in 150 parts by weight of distilled water. In this manner, an aqueous dispersant solution was prepared.

The dye dispersion resin composition, 13 parts by weight of 2-ethylhexyl acrylate, and 0.15 parts by weight of divinylbenzene were added to this dispersant aqueous solution and stirred at high speed to obtain a suspension.

This suspension was heated at a temperature of 80°C for 1 hour, then at 90°C.
The mixture was maintained for 1 hour to carry out suspension polymerization. After the reaction was completed, the obtained polymer was cooled, the solid content was separated, dehydration and washing were repeated, and then dried to obtain a resin composition in which the charge control agent was dispersed.

Next, 100.5 parts by weight of this resin composition (1 part by weight of binder resin)
0.00 parts by weight and 0.5 parts by weight of a charge control agent. ),
3 parts by weight of low molecular weight polypropylene (Viscol 550P manufactured by Kochu Kasei Kogyo ■) and 10 parts by weight of carbon black (MA-8 manufactured by Mitsubishi Chemical Corporation G Kiku) as an anti-offset imparting agent.
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.

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

This developer was applied to a commercially available plain paper electrostatic copying machine (manufactured by Kochu Denki 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 present invention, even after copying 10,000 sheets, clear and beautiful images without background stains could be obtained. Furthermore, no filming was observed on the photoreceptor.

Further, FIG. 3 shows the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier. The measurement was carried out using a charge distribution measuring device manufactured by Hosokawa Micron ■. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is narrow and that there is substantially no amount of oppositely charged toner.

Example 2 Same as Example 1 except that 1 part by weight of the same monoadz-based chromium dye and 0.4 part by weight of ethylene-vinyl acetate copolymer as in Example 1 were used in preparing the dye-dispersed monomer composition. A developer was obtained.

Using this developer, image evaluation was performed in the same manner as in Example 1.゛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, 1
Even after making 0,000 copies, clear and beautiful images without background stains could be obtained. Furthermore, no filming was observed on the photoreceptor.

Further, FIG. 3 shows the triboelectric charge amount distribution of the developer prepared by setting the toner concentration to the carrier at 5% by weight. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is narrow and that there is substantially no amount of oppositely charged toner.

Comparative Example 1 Saponification degree as a dispersant: 8665 mol%, polymerization degree: 230
An aqueous dispersant solution was prepared by dissolving 0.6 parts by weight of partially saponified polyvinyl alcohol (Gohsenol 0H-23, manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) in 150 parts by weight of distilled water.

To this aqueous dispersant solution, 87 parts by weight of styrene, 13 parts by weight of 2-ethylhexyl acrylate, and 0.0 parts by weight of divinylbenzene.
15 parts by weight were added and stirred at high speed to obtain a suspension.

This suspension was heated at a temperature of 80°C for 1 hour, then at 90°C.
The mixture was maintained for 1 hour to carry out suspension polymerization. After the reaction was completed, the obtained polymer was cooled, the solid content was separated, dehydration and washing were repeated, and then dried to obtain a resin composition in which the charge control agent was dispersed.

Next, 100 parts by weight of this resin composition, 25 parts by weight of the same charge control agent O as in Example 1, 3 parts by weight of low molecular weight polypropylene, and 10 parts by weight of carbon black were mixed and melt-kneaded in a twin-screw extruder. It was pulverized using a pulverizer. Next, it is classified using a wind classifier, and the particle size is 5 to 20 μm.
A toner was prepared.

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

Using this developer, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1. Further, FIG. 2 shows the relationship between the number of copies and image density. According to the invention, 10
After making 000 copies, background fog appeared on the image.

Further, FIG. 4 shows the triboelectric charge amount distribution of the developer prepared by setting the toner concentration to the carrier at 5%. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is wide and a considerable amount of oppositely charged toner can be placed.

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

Using this developer, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1. Further, FIG. 2 shows the relationship between the number of copies and image density. According to the invention, 10
After making 000 copies, background fog appeared on the image.

Further, FIG. 4 shows the friction zone distribution of the developer prepared by setting the toner concentration to the carrier at 5% by weight. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is wide and a considerable amount of oppositely charged toner can be placed.

Comparative Example 3 A developer was prepared in the same manner as in Comparative Example 1, except that 1 part by weight of the charge control agent was used.

Using this developer, image evaluation was performed in the same manner as in Example 1. The results are shown in Table 1. Further, FIG. 2 shows the relationship between the number of copies and image density. According to the invention, 10
After making 000 copies, background fog appeared on the image.

Further, FIG. 4 shows the triboelectric charge amount distribution of the developer prepared by setting the toner concentration to the carrier at 5% by weight. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is wide and a considerable amount of oppositely charged toner can be placed.

Example 3 10 parts by weight of the same charge control agent as in Example 1 and 4 parts by weight of ethylene-vinyl acetate copolymer were added to 87 parts by weight of styrene,
The dye was ground in a ball mill under a nitrogen atmosphere for 50 hours to prepare a dye-dispersed monomer composition.

Separately, 0.6 parts by weight of partially saponified polyvinyl alcohol (Gohsenol 0H-23 manufactured by Nippon Gosei Kagaku Kogyo ■) with a degree of saponification of 86.5 mol% and a degree of polymerization of 2300 as a dispersant was dissolved in 150 parts by weight of distilled water. An aqueous dispersant solution was prepared.

This dispersant aqueous solution contains the dye component 11, the resin composition and 2-
13 parts by weight of ethylhexyl acrylate and 0.15 parts by weight of divinylbenzene were added and stirred at high speed to obtain a suspension.

This suspension was heated at a temperature of 80°C for 1 hour, then at 90°C.
The mixture was maintained for 1 hour to carry out suspension polymerization. After the reaction was completed, the obtained polymer was cooled, the solid content was separated, dehydration and washing were repeated, and then dried to obtain a resin composition in which the charge control agent was dispersed.

Next, 11 parts by weight of this resin composition (consisting of 10 parts by weight of binder resin and 1 part by weight of charge control agent), 3 parts by weight of 1 low molecular weight polypropylene, and 10 parts by weight of carbon black were mixed and subjected to twin-screw extrusion. After melt-kneading in a machine, the mixture was pulverized in a jet pulverizer. Next, the toner was classified using an air classifier to produce two rounds of toner having a particle size of 5 to 20 μm.

Using this toner, a developer was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 1. Further, FIG. 1 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. Furthermore, no filming was observed on the angry photoreceptor.

Further, FIG. 3 shows the triboelectric charge amount distribution of a developer prepared with a toner concentration of 5% by weight relative to the carrier. According to the developer according to the present invention, it is shown that the charge distribution width of the toner is narrow and that there is substantially no amount of oppositely charged toner.

[Brief explanation of the drawing]

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 triboelectric charge amount distribution of a developer obtained by the method according to the present invention, and FIG. 4 is a graph showing the triboelectric charge amount distribution of a developer as a comparative example. Figure 1 Figure 2 Atsushi Saku (x yooo)

Claims (5)

[Claims] (1) Crush and disperse the dye and pigment in a polymerizable monomer,
Next, after polymerizing the polymerizable monomer, unreacted polymerizable monomer is removed. (2) The method for producing a dye and pigment dispersion resin according to claim 1, characterized in that the polymerizable monomer is subjected to suspension polymerization or emulsion polymerization. (3) Crushing and dispersing the dye and pigment in the polymerizable monomer,
Next, after polymerizing the above polymerizable monomers, unreacted polymerizable monomers are removed to obtain a dye and pigment dispersion resin, and then,
An electrostatic latent image characterized by adding a binder resin and, if necessary, a characteristic imparting agent to this dye/pigment dispersion resin, melting and kneading it, pulverizing the obtained kneaded material, and classifying it, if necessary. A method for manufacturing toner for development. (4) The method for producing a toner for developing electrostatic latent images according to claim 3, characterized in that the polymerizable monomer is subjected to suspension polymerization or emulsion polymerization. (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 .