JP2002072561A - Method for producing toner for developing electrostatic images - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain toners for electrostatic charge images, having superior quality by recycling fine powder toners. SOLUTION: The fine powder toners, discharged in a toner manufacturing process of steps 1 to 9, are recovered and are granulated in steps 12 and 13. A charge control agent is then added and mixed to and with the granulated fine powder toners in a step 14, and thereafter the mixture is melted and kneaded by using an extruder in a step 15. The kneaded mixture is cooled in a step 16 and is ground coarsely in a step 17. The powder is then recycled to a pulverizing process step of a step 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner for an electrostatic image used in an electrophotographic method, an electrostatic recording medium, and the like, and more particularly to an electrostatic charge for reusing fine powder toner generated in a toner production process. The present invention relates to a method for producing an image toner.

[0002]

2. Description of the Related Art In an electrophotographic system in which a visible image is formed by developing an electric latent image with a developer, an electric latent image is formed on a photoreceptor made of an inductive substance, and then the latent image is developed. The image is developed with a developer, and if necessary, an image formed by the developer is transferred to paper or the like. The dry toner used as a developer in these methods contains a binder resin and a colorant as main components, and if necessary, contains additives such as a charge control agent and a release agent, as is known. It is a thing.

In order to obtain a multicolor image of color, an original is exposed by using a color separation filter, or an image read by a scanner is written and exposed by a laser, and yellow, magenta, and cyan are obtained in the above steps. A color image is formed by superimposing toner images using a color developer.

As shown in FIG. 4, such a toner is generally prepared by dispersing and mixing components such as a binder resin, a colorant, a charge control agent, and a release agent, melt-kneading, and then cooling. , Crush,
It is manufactured so as to have a predetermined particle size by classification. Furthermore, after adding external additives and stirring and mixing, the coarse particles are sieved,
Filled in container. In this manufacturing process, fine powder toner having a particle diameter smaller than a predetermined particle size is generated during pulverization and classification. However, in order to improve product yield, the fine powder toner is collected and recycled. Conventionally, as a method of regenerating the fine powder toner, a method of collecting the fine powder toner generated by pulverization and classification and returning it to the raw material mixing step as it is, or as shown in FIG. After granulating by applying pressure,
A method of returning to the raw material mixing step or the like is used.

For example, Japanese Patent Application Laid-Open No. H05-034976 discloses that a fine powder toner is added to a mixture dispersed and mixed in a dispersion mixing step and reused. Japanese Patent Application Laid-Open No. 6-186775 discloses that a fine powder toner is evenly spread on a toner intermediate after a kneading step, and the fine powder toner is melted by the heat held by the toner intermediate, and then cooled and pulverized. A method of regenerating a product toner having a particle size or more is disclosed. Japanese Patent Application Laid-Open No. H08-069126 discloses a kneading process for fine powder toner, which is separate from the original toner manufacturing process. After melt kneading with an extruder consisting of: returning to the original kneading step of the toner production step, or processing until coarse pulverization and returning after the coarse pulverization step, or processing until classification and returning after the classification step. . Furthermore, Japanese Patent Application Laid-Open No. H10-16
No. 1343 discloses that the fine powder toner discharged in the classifying step is heated or melted or softened, and the obtained melt or softened substance is extruded by a pressure extruder to form a kneaded material before cooling after the kneading step. It is disclosed to be mixed.

[0006]

However, in the fine powder toner recycling method disclosed in Japanese Patent Application Laid-Open No. H05-034976, when the fine powder toner is melted and kneaded again by the kneading machine, the resin molecules are cut off, and the resin is cut off. There has been a problem that a decrease in the molecular weight causes a deterioration in fixing performance and a deterioration in durability performance due to a decrease in mechanical strength.

In the method disclosed in Japanese Patent Application Laid-Open No. 6-186775, the fine powder toner is simply attached to the surface of the pellet-like toner intermediate except when the amount of spraying is very small, and rubbing is performed. The kneaded material and the fine powder toner are not integrated. This is because the heat exchange rate between the kneaded material and the fine powder toner is low, and the properties of the fine powder toner may not be melted or softened except when the softening point is low, and the problem that the throughput of the fine powder toner cannot be increased. there were.

In the method disclosed in Japanese Patent Application Laid-Open No. H08-069126, the flowability is poor due to the large number of particles having a particle diameter of 5 μm or less. There was a problem that a neck phenomenon occurred and the supply could not be performed quantitatively.

In the method disclosed in Japanese Patent Application Laid-Open No. 10-161343, electric power is used to heat the pressure extruder with a heater, so that energy loss occurs, and the softened and melted material remains in the container. There was a problem that the extruder was not completely discharged and the maintainability of the extruder was poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and recycles fine powder toner produced in the process of producing a toner to produce a high quality electrostatic image toner with good productivity. The aim is to provide a method.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a toner for developing an electrostatic image, which recycles a fine powder toner generated in a toner manufacturing process. Add the control agent and mix,
It is characterized in that after being subjected to a melting and regenerating process, it is recycled as a fine powder regenerated toner to a toner production process. In the present invention, by granulating the fine powder toner, it becomes possible to quantitatively supply the fine powder toner during mixing and melt-kneading of the fine powder toner, and by adding a charge control agent to the fine powder toner and re-melting it. Thus, it is possible to manufacture a high quality toner for an electrostatic image by reusing the fine powder toner.

According to a second aspect of the present invention, in the method for producing an electrostatic charge image developing toner of the first aspect, the content of the charge control agent added to the fine powder toner is 0.1 to 1.5% by weight. Features. When the content of the charge control agent is 0.1% or less, the charge amount of the base toner is low, and toner scattering occurs in the machine. At 1.5% or more, problems such as transfer failure on an image occur.

According to a third aspect of the present invention, in the method for producing a toner for developing an electrostatic image of the first aspect, the mixing ratio of the fine powder regenerated toner recycled to the toner production process is set to 10% or more. 10 for toner from raw materials
By mixing the fine-powder-reproduced toner at a mixing ratio of not less than%, the product yield is improved.

According to a fourth aspect of the present invention, in the method for producing a toner for developing an electrostatic charge image according to the first aspect, the fine powder toner generated in each step of the toner production is granulated, then mixed and melt-regenerated. It is characterized by the following. In the present invention, after the fine powder toner generated in each of the coarse pulverization step, the fine pulverization step, and the classification step is granulated, mixed with a charge control agent, and subjected to a melting and regenerating process, the toner production step is performed. Recycled.

According to a fifth aspect of the present invention, in the method for producing a toner for developing an electrostatic image of the first aspect, the melting and regenerating process includes each of melt kneading, cooling, and coarse pulverization.
In the present invention, the fine powder toner generated in the toner manufacturing process is granulated, a charge control agent is added and mixed, and the mixture is melt-kneaded, cooled, and coarsely crushed, and then recycled after the toner manufacturing coarse crushing process. .

According to a sixth aspect of the present invention, in the method for producing a toner for developing an electrostatic charge image of the first aspect, the melting and regenerating process includes each of melt kneading, cooling, coarse pulverization, and fine pulverization. . In the present invention, the fine powder toner generated in the toner production process is granulated, a charge control agent is added and mixed, and the mixture is melt-kneaded, cooled, coarsely pulverized, and finely pulverized. Recycled.

According to a seventh aspect of the present invention, in the method for producing a toner for developing an electrostatic charge image of the first aspect, the melting and regenerating process includes each of melt kneading, cooling, coarse pulverization, fine pulverization, and classification. And In the present invention, the fine powder toner generated in the toner production process is granulated, a charge control agent is added and mixed, and the mixture is subjected to melt kneading, cooling, coarse pulverization, fine pulverization and classification, and then the classification process of the toner production. Will be recycled later.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a process of manufacturing a toner for an electrostatic image according to a first embodiment of the present invention.
Reference numerals 0 to 17 represent a fine powder toner recycling process for reusing the fine powder toner.

First, prior to the description of the toner manufacturing process,
Raw materials of the usable toner will be described. Among the raw materials, a binder resin may be appropriately selected from conventionally known resins alone or in combination, or a modified or polymer alloyed resin. Specifically, for example, polystyrene, polychlorostyrene, polyvinyl toluene,
Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid copolymer,
Styrene-methacrylic acid copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene- and styrene-based copolymer resins such as styrene-maleic acid ester copolymer, acrylic resin, vinyl resin, Examples include ethylene-based resins, polyamide-based resins, polyester-based resins, phenol-based resins, silicon-based resins, xylene-based resins, epoxy-based resins, terpene-based resins, rosin, and modified rosin.

As the colorant, all pigments and dyes conventionally used as toner colorants are applied. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, calco oil blue, Dupont oil red, giraffe yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, hansa yellow, rhodamine 6C lake, chrome Yellow, quinacridone, benzidine yellow, malachite green, malachite green hexalate, oil black, azo oil black, rose bengal, monoazo dyes, disazo dyes, trisazo dyes and the like.

It is effective to add a charge control agent to control the chargeability of the toner. Examples of the charge control agent in this case include a nigrosine dye, a quaternary ammonium salt, an amino group-containing polymer, a metal-containing azo dye, a complex compound of salicylic acid, and a phenol compound. A quaternary ammonium salt, an amino group-containing polymer, and a complex compound of salicylic acid are preferred.

Other additives to be used include silica, aluminum oxides and titanium oxides.
When the main purpose is to impart further high fluidity to the colored particles, the average primary particle diameter is 0.001 to 0.001 as hydrophobized silica or rutile type fine particle titanium oxide.
It can be appropriately selected from the range of 1 μm, preferably in the range of 0.005 to 0.1 μm, and particularly preferred is an organic silane surface-treated silica or titania.

When used as a two-component dry toner, the carrier mixed with the toner may be glass,
Powder having a particle size of about 30 to 1000 μm mainly composed of iron, ferrite, nickel, zircon, silica, or the like, or coating the powder with a styrene-acrylic resin, a silicon resin, a polyamide resin, a polyvinylidene fluoride resin, or the like. It can be used by appropriately selecting from those described above.

Next, a description will be given of a normal toner manufacturing basic process with reference to FIG. In step 1, a plurality of types of raw materials as described above are weighed and blended and mixed. Here, as a mixing device, a double cone mixer, a V-type mixer,
Drum type mixers, super mixers, Henschel mixers, Nauta mixers and the like can be used.

Next, kneading is performed in the kneading step of step 2. At this time, kneading can be carried out using a batch type (for example, a pressure kneader, a Banbury mixer, a two-roller, etc.) or a continuous type extruder. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd., extruder manufactured by KCK, PCM type twin screw extruder manufactured by Ikegai Iron Works, Kuriyama Seisakusho A twin-screw extruder, a co-kneader manufactured by Bus, and the like are used.

The barrel of the extruder used in this step is divided into a plurality of parts, inside which heating means such as an electric heater and cooling means such as a cooling pipe are provided. It is something that is regulated. A biaxial screw meshes in the barrel and is 100 to 5 in the same direction.
A screw that rotates at a high speed of about 00 rpm is provided. The configuration of the screw can be selected as appropriate, but it may be composed of a feed screw and a kneading screw. The toner raw material mixture is fed into the feed screw from the hopper by a screw feeder, gradually preheated, and a strong share is applied by the kneading screw. It changes from a state to a molten state. Furthermore, by providing a second kneading portion screw at the rear or changing the screw shape and configuration to a high temperature state in which the kneaded material is sufficiently melted, it is possible to improve the wettability of the resin and the colorant. it can. In addition, it is preferable to provide a plurality of vent ports behind the portion where the kneaded material is in a molten state and to vent the gas.Furthermore, a part or all of the vent ports is vacuum-evacuated by a pump or the like,
This is preferable because the filling state of the kneaded material is improved, the dispersibility is improved, and the efficiency of removing the exerted component is improved.

The number of shafts of the continuous extruder is preferably one or two. The number of screw threads may be appropriately selected from two or three in consideration of dispersibility, productivity, kneading temperature and the like. The size of the extruder is preferably such that the screw feed part, kneading part and a plurality of vent ports of the kneaded material can be sufficiently arranged, the barrel inner diameter is D (mm), and the length from the raw material supply port to the outlet is L / D when L (mm) is 20
Or more, preferably 25 or more.

The kneaded material is rolled by a rolling roll or the like, and is cooled by air cooling, water cooling or the like in the cooling step of step 3. Then
The material is coarsely pulverized by a crusher, a hammer mill, a feather mill or the like (step 4), finely pulverized by a jet mill, a high-speed rotor rotary mill or the like (step 5), and pulverized stepwise to a predetermined toner particle size. After the pulverization, in Step 6, the particles are classified by an inertia classification type elbow jet, a centrifugal force classification type microplex, a DS separator, and the like, whereby a classified toner having an average particle diameter of 3 to 15 μm is obtained.

Further, when the toner is externally added, a predetermined amount of various known additives is blended with the classified toner, and the mixture is stirred and mixed by a high-speed stirrer such as a super mixer, a Henschel mixer or the like, which gives a shearing force. (Step 7), a sieving process for removing dust and the like mixed in the manufacturing process is performed (Step 8), and the toner is filled in a container as final toner (Step 9).

Next, the fine toner recycling process will be described. In the above manufacturing process, fine powder toner having an average particle size smaller than the desired average particle size of the classified toner, such as fine particle toner generated at the time of classification and fine toner collected by the collection device, is generated. In order to reuse these, the fine powder toner generated in the fine pulverizing step of Step 5 (hereinafter referred to as fine powder A).
And collecting the fine powder toner (hereinafter referred to as fine powder B) generated in the classifying step of Step 6 (Steps 10 and 1).
1). Here, the average particle size of the toner is measured using a commercially available particle size distribution analyzer, for example, Coulter Counter TA of Coulter Inc.
-II.

The recovered fine powder A and fine powder B are pressed and granulated by a granulator in steps 12 and 13, respectively, and then sent to a mixing step.

In the mixing step 14, the charge control agent is added to the collected toner of the granulated fine powder A and fine powder B in an amount of 0.1 to 0.1%.
It is added and mixed so as to have a content of 1.5%, preferably 0.3 to 1.3%. If the charge control agent is 0.1% or less, the charge amount of the base toner is low, and toner scattering occurs inside the machine. On the other hand, if it is 1.5% or more, problems such as transfer failure on an image occur.

The recovered toner to which the charge control agent has been added at a ratio of 0.1 to 1.5% is melt-kneaded in step 15. The extruder used in this melt kneading step is Step 2
As in the kneading step, a batch type or a continuous type can be used, but a continuous type is preferred from the viewpoint of productivity. The basic structure of the extruder may be the same as that of the extruder used in the kneading step of step 2. However, the recovered toner granulated is supplied to make it melt in the extruder, and the molecular weight of the recovered toner is increased. In order to suppress cutting, the screw is preferably mainly a feed screw, more preferably a feed screw. The vent port may be provided as needed, and the L / D is preferably 35 or less, and more preferably 30 or less, in order to reduce molecular breakage of the collected toner.
The number of screw axes may be one or two, and the number of threads may be two or three. However, considering productivity and economy, one and two threads are preferable. In addition, melt kneading may be carried out using a batch type open-type two rolls, but productivity is lower than that of a continuous type.

The kneaded product of the fine powder regenerated toner that has passed through the melt kneading step of step 15 is cooled in the cooling step of step 16, coarsely pulverized in the coarse pulverizing step of step 17, and then returned to the fine pulverizing step of step 5. . The fine powder regenerated toner supplied to the fine pulverizing step has a charge control agent content different from that of the toner from the raw material, but if used in a mixing ratio of 10% or more, the product yield is improved.

As shown in FIG. 2, the fine powder regenerated toner is further pulverized by providing a fine pulverizing step of step 18 as shown in FIG. May be returned to the classification step. Also, as shown in FIG. 3 showing the manufacturing process of the toner for an electrostatic charge image according to the third embodiment, after the fine pulverizing step of step 18 and the classification step of step 19, the process returns to the mixing step of step 7. You can also.

As is clear from the above description,
According to the third embodiment, the fine powder toner having an average particle diameter or less generated in each step can be granulated, and can be reused by adding a charge control agent and regenerating and melting. After the pulverization step, the fine pulverization step, or the classification step, the mixing ratio is returned to 10% or more to the corresponding production step of the toner from the raw material, thereby improving the product yield and improving the productivity. A good toner can be obtained, and a high-quality toner with little change in the molecular weight of the resin and excellent in fixing properties, durability, uniformity, storage properties, image characteristics, and the like can be stably manufactured.

[0037]

The present invention will be described below in detail with reference to examples. Example 1 As shown in Table 1, for each of the four types of pigments, a polyol-based resin and a negative charge-based control agent were mixed at a predetermined weight ratio, then melt-kneaded in a twin-screw extruder, and cooled and solidified. The product is roughly pulverized with a hammer mill to a size of about 2 mm.
Of yellow, magenta, cyan and black were obtained.

[0038]

[Table 1]

The center particle size generated in this coarse pulverization step is 5 μm.
The following fine powder toner was charged into a roller compactor to granulate, and then a negative charge control agent was added at a content of 0.8%, mixed, and melt-kneaded by a twin screw extruder. Subsequently, through a cooling step and a coarse pulverizing step, a coarsely pulverized product of the fine powder regenerated toner was obtained. The coarsely pulverized regenerated toner is added to the coarsely pulverized toner from the original raw material at a mixing ratio of 10%,
It was finely pulverized with an S-2 type jet pulverizer (manufactured by Nippon Pneumatic Industries, Ltd.). Further, fine powder was removed by a classifier to obtain each color toner having a distribution of an average particle diameter of 8.5 μm. For 2 kg of each color toner, surface silica was added to 2.kg.
The mixture was added at a weight ratio of 0%, mixed by a Henschel mixer, and the toner was sieved to obtain a dry toner of each color.

Example 2 Production of a dry toner under the same conditions as in Example 1 except that the negatively charged system controlling agent was added to the granulated fine powder toner at a content of 0.5%, mixed, and regenerated and melted. Was done.

Example 3 A dry toner was manufactured under the same conditions as in Example 1 except that the fine powder regenerated toner was added to the toner from the raw materials at a mixing ratio of 30%.

Example 4 Except that the fine powder toner was regenerated and melted by an open double roll,
A dry toner was manufactured under the same conditions as in Example 3.

Example 5 In the same manner as in Example 1, the raw materials were mixed, melt-kneaded, cooled,
After coarse pulverization, it was further performed to fine pulverization. The fine powder toner having a center particle diameter of 5 μm or less generated in the coarse pulverizing step and the fine pulverizing step was regenerated and melted in the same manner as in Example 4, cooled, coarsely pulverized, and further subjected to fine pulverization. This finely pulverized regenerated toner is added to the finely pulverized toner from the original raw material at a mixing ratio of 30%, and the fine powder is removed by a classifier.
Each color toner having an average particle size distribution of 8.5 μm was obtained.
Thereafter, the same processing as in Example 1 was performed to obtain a dry toner of each color.

Example 6 In Example 5, the production of the toner from the raw material was performed up to the classification step, and the regenerated and fused toner was used using the fine powder toner generated in each of the coarse pulverization, fine pulverization and classification steps. Recycled after the classification process of toner production from raw materials. Other than that, the treatment was carried out under the same conditions as in Example 5 to obtain dry toner of each color.

Comparative Example 1 To the raw materials having the weight ratios shown in Table 1, 20 parts of the fine powder toner generated in each step of the toner production shown in Example 1 was added and mixed.
Dry toner of each color was obtained through a toner manufacturing process after the kneading process.

Comparative Example 2 The fine powder toner shown in Comparative Example 1 was put into a coarse pulverizing step in a usual toner production to produce a dry toner of each color.

Comparative Example 3 A dry toner was produced in the same manner as in Example 1, except that the granulated fine powder toner was regenerated and melted without adding a charge control agent.

Comparative Example 4 The fine powder toner having a center particle diameter of 5 μm or less discharged in the classifying step of toner production was regenerated and melted in the same manner as in Comparative Example 3, and was subjected to coarse pulverization. At a mixing ratio of Otherwise, a dry toner was manufactured under the same conditions as in Example 1.

With respect to each of the dry toners of Examples 1 to 6 and Comparative Examples 1 to 4, 5 parts of the dry toner and 95 parts of a silicone resin-coated carrier of about 80 μm were stirred and mixed to obtain a two-component developer. Then, in order to confirm the quality of the examples and comparative examples, a four-color two-component developer was prepared using a commercially available plain paper full-color electrophotographic copying machine (imagio col manufactured by Ricoh Co., Ltd.).
or 2850), continuous evaluation of 20,000 sheets was performed, and the charge amount, heat-resistant storage stability, reverse charging characteristic, and toner scattering in the machine were evaluated as images and matching characteristics. Table 2 summarizes the results. In Table 2, the unit of the charge amount is -μC / g, and the evaluation of toner scattering and image quality is ◎ = excellent, ＝= good, Δ = slightly inferior, ×
= Bad.

[0050]

[Table 2]

As is clear from Table 2, in the examples of the present invention, the toner having excellent image characteristics and matching characteristics could be obtained by recycling the fine powder toner.

[0052]

As described above, according to the present invention, the charge control agent is added to the fine powder toner, mixed, regenerated and recycled, so that the fine powder toner can be reused and the change in the molecular weight of the resin is small. Thus, an electrostatic image toner having excellent quality performance such as fixing performance, durability performance and image characteristics can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 is a process chart showing a process of manufacturing an electrostatic image toner according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing a process of manufacturing an electrostatic image toner according to a second embodiment of the present invention.

FIG. 3 is a process diagram showing a process of manufacturing an electrostatic image toner according to a third embodiment of the present invention.

FIG. 4 is a process chart showing an example of a conventional process for producing an electrostatic image toner.

Claims (7)

[Claims] In a method of manufacturing a toner for developing an electrostatic image, which recycles fine powder toner generated in a toner manufacturing process, after granulating the fine powder toner, a charge control agent is added, mixed, and melted and regenerated. A method for producing a toner for developing an electrostatic image, wherein the toner is recycled as a fine powder regenerated toner after the treatment to a toner production process. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the content of the charge control agent added to the fine powder toner is 0.1 to 1.5% by weight. A method for producing an electrostatic image developing toner. 3. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the mixing ratio of the regenerated fine powder to be recycled in the toner production step is 10% or more. Manufacturing method of toner. 4. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the fine powder toner generated in each step of the toner production is granulated, then mixed and melt-regenerated. Of producing a toner for developing electrostatic images. 5. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the melting and regenerating process includes each of melt kneading, cooling, and coarse pulverization. Manufacturing method. 6. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the melting and regenerating process includes each of melt kneading, cooling, coarse pulverization, and fine pulverization. A method for producing a developing toner. 7. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the melting and regenerating treatment includes melt kneading, cooling, coarse pulverization, fine pulverization, and classification. A method for producing a toner for developing a charge image.