JP3438557B2 - Magnetic toner and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner used for developing an electrostatic charge image in electrophotography, electrostatic recording and the like, and a method for producing this magnetic toner.

[0002]

2. Description of the Related Art In copying machines and printers utilizing electrophotography, electrostatic recording, etc., an electrostatic charge image formed on an image bearing member such as a photoconductor is developed with a developer, and a toner image after development is developed. Is transferred to a transfer paper and then fixed to form a final toner image. Conventionally, as a developer for developing an electrostatic image, a two-component developer including a carrier and a toner and a one-component developer (magnetic toner) not using a carrier are usually used. As the toner, positively chargeable toner and negatively chargeable toner are known, and in order to impart positive chargeability or negative chargeability to the toner, a charge control agent must be contained in the toner or the carrier must have a predetermined amount. It has been practiced to attach a coating layer that imparts the above-mentioned chargeability. Further, a release agent such as wax for imparting releasability, a colorant, and an additive such as a magnetic material for imparting magnetism to the toner are internally added to the toner as required.

FIG. 5 shows a conventional manufacturing method of the toner used for developing these electrostatic images, taking magnetic toner as an example. That is, as shown in FIG. 5, first, a thermoplastic resin which is a binder as a main component of the toner, a magnetic powder, a charge control agent, a release agent such as wax, and a colorant, if necessary, are mixed in a ball mill, It is premixed by a mixer such as a Henschel mixer. The pre-mixed mixture was heated and melted and kneaded by using a kneading device such as a heating roll, a kneader, a single-screw or twin-screw extruder, cooled and solidified, then coarsely crushed by a hammer mill or the like, and then finely pulverized by a jet mill or the like. After that, the finely pulverized product is classified by a classifier, and a product having a desired particle size is selectively separated from the finely pulverized product, spheronized, and an external additive is added if necessary to obtain a product toner.

By the way, in the above conventional manufacturing method, the necessary constituent materials of the toner are mixed at a ratio desired as the final toner in the pre-mixing step, and then the mixture is heated and kneaded to an extent deemed sufficient, but after pulverization and classification. The ratio of the constituent components of the toner in the desired particle size distribution taken out is not the same as the initial mixing ratio, and the mixing ratio of the toner constituent materials in the toner is different even between toners having different particle sizes after classification. The current situation is that (distribution) is different. Conventionally, the initial mixing ratio of the toner constituent materials is set to an amount in consideration of this variation so that the toner having a desired particle diameter obtained by classification is constituted by a desired constituent material component ratio on average. Although it is dealt with by adopting a method, it is difficult to finely adjust the toner constituent material component ratio of the final toner by this method, and further, the friction of the toner from which the toner constituent material component ratio of the final toner is obtained. Since it also affects the charging property, it has been a major obstacle in obtaining the best development image quality. The non-uniform dispersion of the constituent materials is remarkably observed in the production of a magnetic toner using wax as a toner constituent component, and a magnetic toner having a non-uniform constituent dispersion is obtained with excellent development characteristics and development stability. Not only is it impossible to do so, but especially for waxes due to the deterioration of the charging characteristics of the toner and the non-uniformity of triboelectrification due to the release of the wax from the toner in the subsequent classification process or in the developing device such as a copying machine. This is a cause of problems such as a decrease in transfer rate, a decrease in image density, fog, stains inside the apparatus due to toner dust, and surface contamination of a photosensitive member and a development carrier due to separated wax. Therefore, it is important to uniformly disperse the wax, the charge control agent, the magnetic substance and the like in the thermoplastic resin which is the binder resin in the melt-kneading step during the production of the toner.

From these circumstances, several attempts have been made to improve the uniform dispersibility of the constituent materials of the toner. For example, Japanese Patent Laid-Open No. 6-95433 describes that two kneading parts are provided in one kneader having two rollers to improve the distributability. According to this method, the dispersibility is improved to some extent by providing the toner kneading section at two places, but in the heat kneading by the two rollers, the main component resin is sheared during the heat melting and kneading, and the molecular chain Cutting occurs as a function of shear size and time. For this reason, a decrease in the molecular weight of the main component resin is unavoidable, the viscoelastic properties of the toner are changed, the performance of the toner is significantly impaired, and the dispersion uniformity is not yet sufficient. However, the results were not necessarily satisfactory.

On the other hand, in a copying machine or a printer, a large amount of toner is collected and collected in a so-called cleaning step of cleaning the toner remaining on the surface of the photoconductor after the toner image transfer, and this collection and collection is carried out. The toner is returned to the toner manufacturing process and reused as a toner forming material, and the ultrafine powder particles generated in the pulverizing process during toner manufacturing and the fine particles having a particle size equal to or smaller than the desired particle size when separating the toner having a desired particle size in the classification process are used. It has also been studied to reuse the collected powder in the filter bag or the coarse powder remaining on the sieve in the classification step as a toner-forming material. However, since the uniformity of the distribution ratio of the constituent material components of the toner manufactured by the conventional method is not sufficiently ensured, the ratio of the constituent material components of the collected and collected toner is unknown, and the toner is mixed with the new material as it is. When you manufacture toner,
The composition ratio of constituent materials of the finished toner is unknown, stable toner cannot be supplied, and the distribution ratio of constituent materials is not sufficiently uniform, resulting in difficulty in recovery or reuse of collected toner. It was JP-A-6-2
In Japanese Patent No. 69131, it is described that the toner collected from the market and the toner collected in the filter bag are mixed and supplied together during the kneading of the new material in the heating kneader, and are reused. Even if the measures are taken, a toner having sufficient dispersibility has not been obtained from the conventional experience. These toner reuse plans are not only a problem of reducing the manufacturing cost, but also an important issue for effectively using resources and dealing with environmental problems, which are increasingly required in recent years.

[0007]

As described above, as a magnetic toner used for developing an electrostatic charge image and a method for producing this magnetic toner, toner constituent materials are uniformly dispersed in all toners. The classified toner particles have the same toner constituent material component ratio, the toner development characteristics such as charging characteristics are excellent, and an image with good image quality can be stably formed. Alternatively, there has been a strong demand for a toner that is highly economical because it can be reused as a trapped toner and that is environmentally friendly, and a method for producing such a toner.

The present invention has been made for the purpose of solving the problems and demands of the prior art and providing a magnetic toner having excellent characteristics and a method for producing the magnetic toner.

That is, an object of the present invention is to provide a magnetic toner in which the constituent materials of the toner are uniformly dispersed regardless of the toner particle size, and which is excellent in developing characteristics, and a method for producing the toner. Another object of the present invention is to provide a magnetic toner and a method for producing the toner, in which the mixing ratio of the toner raw materials and the ratio of the raw material components of the product toner are substantially the same. Another object of the present invention is to provide a magnetic toner capable of reusing a toner collected from a copying machine or a printer, a collected toner at the time of manufacturing a toner as a raw material at the time of manufacturing a new toner, and a method for manufacturing the toner. Is. Further objects of the present invention will be apparent from the following description.

[0010]

Means for Solving the Problems As a result of intensive studies and studies, the present inventors have found that, as a thermoplastic resin that is a binder component of a magnetic toner, for example, when the thermoplastic resin is polymerized, the polymerization is finely divided. Wax fine particle-dispersed thermoplastic resin obtained by carrying out in the presence of a dispersed wax, or obtained by adding a wax to a solution or dispersion of a thermoplastic resin and then distilling off a solvent or a dispersion medium. The thermoplastic resin in which the wax is finely dispersed is heated and kneaded together with the charge control agent, cooled and coarsely crushed, and then the first coarsely crushed material is again heated and kneaded together with the magnetic fine powder to obtain a toner constituent material. The present invention is based on the finding that it is possible to produce a magnetic toner in which is uniformly dispersed.

That is, in the first aspect of the present invention, the wax fine particle-dispersed thermoplastic resin is heated and kneaded together with the charge control agent, cooled and then coarsely crushed, and the first coarsely crushed material is again heated and kneaded together with the magnetic fine powder. Magnetic toner characterized by
Is a manufacturing method. A second invention of the present invention is obtained in the above-mentioned first invention, wherein the wax fine particle-dispersed thermoplastic resin is obtained by polymerizing the thermoplastic resin in the presence of the wax resin. A method of manufacturing a magnetic toner characterized by the above. The third invention of the present invention is
In the above first invention, the wax fine particle-dispersed thermoplastic resin is obtained by adding wax to a solution or dispersion of a thermoplastic resin and then distilling off a solvent or a dispersion medium. This is a method for manufacturing a magnetic toner. A fourth invention of the present invention is the method for manufacturing a magnetic toner according to any one of the first to third inventions, characterized in that the raw material powders are mixed in advance to knead to prepare a premixed product. . A fifth invention of the present invention is the above-mentioned first to fourth invention, wherein the first kneaded material and the heated kneaded material of the magnetic powder are cooled, crushed, and then classified, and the coarse powder outside the predetermined particle size range and And / or a fine powder is removed. The sixth invention of the present invention is, in the above-mentioned first to fifth inventions, in at least one step up to the reheat kneading step including the reheat kneading step, fine powder collected during pulverization,
A method for producing a magnetic toner, comprising adding and mixing a classified coarse powder and / or a classified fine powder. In a seventh aspect of the present invention, in the first to sixth aspects of the invention, the toner produced by the method for producing a magnetic toner of the present invention and collected and collected in the cooling step of the copying machine is reheated and kneaded. A method for producing a magnetic toner, comprising adding and mixing in at least one step up to the reheating and kneading step. An eighth invention of the present invention is a magnetic toner manufactured by the method for manufacturing a magnetic toner according to the first to seventh inventions.

The magnetic toner of the present invention and the method for producing the magnetic toner will be described in more detail below. First, in the magnetic toner of the present invention, a wax fine particle dispersed thermoplastic resin is used as a constituent material. As the wax fine particle-dispersed thermoplastic resin in which the wax used in the present invention is finely dispersed, as described above, for example, when the thermoplastic resin is manufactured, the wax is finely dispersed in the reaction solution in advance. Wax fine particle dispersion heat produced by adding wax to a wax fine particle dispersion thermoplastic resin or a solution or dispersion of a thermoplastic resin produced by carrying out a polymerization reaction from Any resin may be used as long as wax is uniformly dispersed in the thermoplastic resin (wax-dispersed resin) such as a thermoplastic resin. A method for producing the thermoplastic resin in which the wax is finely dispersed and the thermoplastic resin in which the wax is finely dispersed are described in, for example, JP-A-57-2.
It is already known as described in 11157 and the like. More specifically, the method for producing a wax-dispersed resin will be described. 1) A method in which a wax is dispersed in a solvent and then a monomer and an initiator are added to carry out resin synthesis, and 2) A wax is dispersed in the monomer and the solvent to synthesize the resin. 3) Method of performing resin synthesis by suspension polymerization in a state where all are dispersed with a dispersant and the like, 4) Resin synthesis is performed by dispersing a wax in a solvent, adding an initiator, and then adding a monomer. Various methods are known, such as the method 5) a method in which a monomer and a wax are bulk polymerized to synthesize a resin. In the present invention, good results can be obtained by any of these conventionally known methods as long as the wax is uniformly dispersed in fine particles in the thermoplastic resin.

By the way, as the wax and the polymer monomer used as the raw materials for producing the wax fine particle dispersed thermoplastic resin used in the present invention, any of the wax and the polymer monomer conventionally used in the production of toner may be used. You can For example, examples of the wax include olefin wax such as polyethylene, polypropylene and polybutylene, paraffin wax,
Examples thereof include waxes such as microwax and montan wax, and those having releasability such as polyamide. These waxes have a melting point of 70 to 155 ° C., 1
The melt viscosity at 40 ° C. is preferably 800 cP or less, the melting point is more preferably 75 to 145 ° C., the melt viscosity at 140 ° C. is more preferably 500 cP or less, and the melting viscosity at 80 to 135 ° C. and 140 ° C. is further preferable. Is particularly preferably 300 cP or less.

Further, as the monomer forming the thermoplastic resin which can be used in the present invention, styrene such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, vinyltoluene and its substitution products; Acrylic esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate; methyl methacrylate, ethyl methacrylate,
Methacrylic acid esters such as n-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate; acrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; maleic acid, maleic acid ester, etc. Unsaturated carboxylic acids, unsaturated carboxylic acid esters; olefins such as ethylene, propylene and butadiene, and diolefins. Further, the monomer does not have to have a vinyl group, and may be one used for producing a polycondensate such as polyester, polyether, polyamide, epoxy resin, and phenol resin. That is, the thermoplastic resin used in the present invention may be not only a vinyl polymer but also a polycondensation resin such as polyester. The resin may be partially crosslinked with a crosslinking agent or may have a plurality of molecular weight peaks. In short, any one can be used as long as it is suitable as the binder resin of the toner.

As the polymerization initiator, any conventionally known initiator can be used, for example, benzoyl peroxide,
Lauroyl peroxide, tertiary butyl hydroperoxide, tertiary butyl peroxybenzoe
, Ditertiary butyl peroxide, cumene hydroperoxide, dicumyl peroxide, azoisobutyronitrile, azobisvaleronitrile and the like are usually preferably used. Then, the polymerization temperature is also appropriately selected according to the types of the monomer and the initiator used.
The ratio of the initiator to the vinyl monomer used is
0.2-5% by weight is common.

As the charge control agent, known positive charge or negative charge control agents can be used alone or in combination. The charge control agent may be used in an amount necessary to obtain the desired charge amount of the toner, and is preferably about 0.05 to 10 parts by weight with respect to 100 parts by weight of the resin.
Examples of positive charge control agents include nigrosine dyes,
Examples include primary ammonium salt-based compounds, triphenylmethane-based compounds, imidazole-based compounds, and polyamine resins. Further, as the negative charge control agent, Cr, Co, Al,
Examples include metal-containing azo dyes such as Fe, metal salicylic acid compounds, metal alkylsalicylic acid compounds, and carlix arene compounds.

In the present invention, a magnetic powder is used. As the magnetic material that can be used in the present invention, an alloy, a compound, etc. containing a ferromagnetic element which has been conventionally used in the production of magnetic toners. Any one may be used. Examples of these magnetic materials include magnetite,
Iron oxides such as maghetite and ferrite, or compounds of divalent metals and iron oxides, metals such as iron, cobalt, nickel or aluminum, cobalt, copper of these metals.
Mention may be made of alloys of metals such as lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof. These magnetic materials preferably have an average particle size of 0.1 to 2 μm, more preferably 0.1 to 0.5 μm. The content of the magnetic substance in the toner is about 20 to 200 parts by mass, preferably 40 to 15 parts by mass with respect to 100 parts by mass of the thermoplastic resin.
It is 0 part by mass.

Further, in the present invention, a colorant and other internal additives may be used if necessary. Examples of colorants known to be used in the production of toners include fatty acid metal salts, various carbon blacks, phthalocyanine-based, rhodamine-based, quinacridone-based, triallylmethane-based, anthraquinone-based, azo-based, diazo-based, and the like. Examples include dyes and pigments. Further, in the toner of the present invention, an external additive is used if necessary. Examples of this external additive include polyvinylidene fluoride, zinc stearate, lubricants such as polytetrafluoroethylene, cerium oxide, silicon carbide, strontium titanate, tungsten carbide, abrasives such as calcium carbonate, colloidal silica, aluminum oxide. , And fluidity-imparting agents such as titanium oxide.

A method of manufacturing the magnetic toner of the present invention will be briefly described with reference to FIG. 6 showing an embodiment thereof. First,
Wax fine particle dispersion thermoplastic resin powder and charge control agent powder are weighed and thoroughly mixed by a mixer (mixing step) to produce a pre-mixture, and then the powder mixture is melt-kneaded by a heat-melt kneader (kneading step ), After cooling (cooling step), coarse crushing (coarse crushing step). After thoroughly mixing the coarsely pulverized first coarsely pulverized product and the magnetic fine powder again with the mixer (second mixing step), the mixture is melt-kneaded with the heat-melt kneader (second kneading step), and after cooling. (Second cooling step), coarse pulverization, and then fine pulverization (pulverization step). This finely pulverized material is classified, powders having a particle diameter other than the desired particle diameter are removed (classification step), and after spheroidizing treatment is added, an external additive is added (external addition step), After mixing, the mixture is passed through a sieve (screening step) and then filled in a container (focusing step) to obtain a product toner.

The mixing and kneading conditions of the materials in the method for producing the magnetic toner of the present invention will be described in more detail below. By the way, the inventors of the present invention, in the conventional manufacturing method of the magnetic toner, the addition timing of the raw material, the mixing method,
Various combinations of kneading methods were examined. In this study, using a kneader with two material input ports,
Regarding the method of heating and kneading by charging the charge control agent from one port and the magnetite fine powder from the other, and the type of kneader, as well as the number and shape of the feed screws and the conditions such as the feeding speed and temperature. Various modifications were made to examine the dispersibility of the material in the toner, but no kneaded product having good dispersibility was obtained in any of the cases.

However, after the charge control agent is added to the finely pulverized wax fine particle thermoplastic resin and well mixed, the mixture is heated and melted and kneaded by a kneader, and the extruded product is cooled and then pulverized, and a predetermined amount of magnetic property is added thereto. After adding fine powder (eg magnetite etc.) and thoroughly mixing with a mixer, heat and melt knead again with a kneader, extrude as in the previous step, cool and crush, then move to the fine crushing step. As a result of finely pulverizing and then classifying and measuring the distributive property, the distributive property of the raw material is good, and also the ratio of constituent materials of constituents of each kneaded meat throughout the manufacturing process, that is, the distributive property is almost the same. It has been found. This magnetic toner had a good dispersibility even with the ultrafine powder collected in the filter bag. It was also found that when this method was adopted, the molecular chains of the main component resin were not severed and the viscoelastic behavior was hardly impaired.

The production method of the present invention was examined by variously changing the experimental conditions such as the mixing apparatus of raw material powder, the mixing conditions, the supply amount of the raw material to the kneading machine, the processing temperature and the specifications of the kneading machine. However, even if the kneading machine, the kind of the kneading condition, and the like and the conditions are changed, the dispersibility of the material in the toner, the toner characteristics, and the like are not significantly changed. That is, in the present invention, first, a wax fine particle-dispersed thermoplastic resin is mixed with, for example, a charge control agent other than magnetic powder, and the first kneading is carried out by a kneading machine, followed by cooling once and cooling It is only necessary to go through the step of adding and mixing a magnetic fine powder such as magnetite to the subsequent coarsely crushed product and then performing the second heating and kneading with a kneader. It has been found that the mixing and kneading conditions, the mixer, the kneading device, and the like may appropriately employ the devices and conditions conventionally used for producing magnetic toners. Therefore, for example, as a kneading machine, a uniaxial type which is usually used in a kneading step of toner, in which a large shear is not applied to the resin during kneading,
Biaxial kneader (eg, PCM made by Ikegai, KEX made by Kurimoto, KCC made by KCC, ZSK made by Warner)
Etc.) can be used arbitrarily. Then, in these studies, it was not possible to obtain a magnetic toner having good distributability by first mixing a magnetic powder such as magnetite with the wax fine particle-dispersed thermoplastic resin, and after cooling once,
It was unexpected that a uniform dispersion could not be obtained by mixing magnetite by continuous heating and kneading without coarse pulverization, and therefore efficient dispersion mixing could not be performed.

When the reason why such a result is obtained is inferred, a substance having a small molecular weight such as a charge control agent and having a good compatibility with a resin or the like has a specific gravity like a magnetic substance. Is also large, it is relatively easy to mix and disperse unlike the case where compatibility with the resin is not considered, and if a material with good compatibility with the resin is mixed in advance, it will be dispersed due to the presence of a substance such as a magnetic substance. Is believed to be undisturbed. In addition, by adopting the above-described two-step kneading process, the mixing and dispersing time in the heating kneader can be reduced, and the share applied to the resin can be reduced. It is considered that the molecular chain of the resin is less broken, and the viscoelastic behavior of the main component resin itself, and by extension, the toner, does not change. However, these ideas are merely speculations by the present inventors and are not intended to limit the present invention.

As described above, the conditions of pre-mixing, heat-melt kneading, crushing, etc., in producing the magnetic toner according to the present invention are as follows.
A wide range of conditions can be utilized, including those used in conventional magnetic toner manufacture. For example, in the first premix, resin pellets or chips less than 10 mm, 1-100
Using a Henschel mixer, a charge control agent having a particle size of about μm is rotated at a rotation speed of 1000 to 4000 rpm for 1 to 1.
It may be mixed for 15 minutes, then melt-extruded at a discharge temperature of about 150 ° C. ± 50 ° C., cooled, and then roughly crushed to a size of about 1 to 5 mm. Of course, the degree of crushing may be larger or smaller than this. In the second pre-mixing, the above-mentioned crushed product and the magnetic fine powder of magnetite or the like having a particle size of less than 1 μm may be mixed under the same conditions as in the first pre-mixing. Can be done.

By the way, since the magnetic toner of the present invention has good dispersibility of the raw material, the toner produced by the present invention may be a transfer residual toner when an image is formed by a copying machine or the like, or toner production. The material components of the collected or collected toner such as the collected toner in the filter bag collected therein are almost the same as those of the newly manufactured toner. Therefore, these collected or collected toners can be used as a part of raw materials when manufacturing a new toner.
The toner experimentally produced by the present manufacturing method was subjected to an image output test with a commercially available Canon NP-4145 machine, and the recovered toner obtained at that time was sieved to remove impurities such as paper dust. During the second pre-mixing step of the toner manufacturing process, a kneading test was conducted in which the same amount as the new material was added in several steps, and the distributability in the subsequent steps was tested. No significant difference was observed in comparison with the case of the material alone. Further, the situation was investigated by introducing the recycled toner at the time of the first mixing, but almost the same results were obtained, so it is considered that either of the introducing steps may be performed. Further, the timing of introducing the recycled toner or the like is not limited to this, and may be introduced at the time of kneading, for example. This test is on a small scale on a test machine and it is considered optimal to add up to 30% of the new material during the second mixing.

Further, the ultrafine powder toner collected in the filter bag at the time of crushing and classifying the toner in the final toner manufacturing step was added to the new toner manufacturing step as in the above-mentioned recycled toner to manufacture the toner. There was no problem. In addition, it is appropriate to add the collected amount of the filter bag, preferably up to 30% of the amount of the new material, at the time of the second mixing.

Further, recycled toner (transfer residual toner)
A new toner was produced by using the toner collected in the filter bag and the toner collected in the filter bag, but no abnormality in dispersibility was observed in this toner.

[Quantitative Method of Toner Constituent Components] In the following Examples, Comparative Examples, and Reference Examples, each constituent component in the toner was quantified by the following method.

(Determination of Wax Amount in Toner) The amount of wax in the toner is determined by a differential scanning calorimeter DSC-520.
It was carried out by measuring the endothermic amount of the substance according to 0 (manufactured by Seiko Denshi KK). By this measurement, a curve having an endothermic peak peculiar to wax is obtained. The measurement for obtaining the calibration curve is 56.5% by weight in total of thermoplastic resin (styrene / acrylic resin) and wax (polypropylene), 1.5% by weight of charge control agent (nigrosine dye) and magnetic substance ( Magnetite) 40.0% by weight, and only the wax content in the toner is 1.0, 1.5, 2.0, 2.
6 produced to be 5, 4.0 and 10% by weight
It was carried out by measuring the amount of endotherm using one kind of magnetic toner. The integrated value of the peak of the curve of each measured value is 1, respectively.
1.57, 2.13, 2.63, 3.77 and 9.4
It was 7 mJ / mg. This value, the vertical axis is the amount of heat absorption,
When the horizontal axis is plotted as the compounding ratio, the formula found between the integrated value of the peak of the curve of each measured value and the wax amount; y = 0.932x + 0.163 (y: endothermic amount mJ / mg, x: wax Mixing ratio%, R
² = 0.9987) was calculated from the graph (see Figure 1). Then, the amount of wax in the toner ground product was quantified using this calculated calibration curve.

As for the dispersibility of the wax, the solubility method utilizing the difference in solubility when the toner is dissolved in a solvent, the wax is selectively dyed with ruthenium oxide (RuO ₄ ) and the transmission type is used. The wax selective staining method observed with an electron microscope or the nuclear magnetic resonance method may be considered, but the solubility method does not have good accuracy, and it takes a long time, so it cannot be used in a system that shares polypropylene and polyethylene. I didn't adopt it. Furthermore, the selective dyeing method of wax could not give clear results. The nuclear magnetic resonance method was not adopted because it is not suitable for routine measurement.

(Quantitative determination of the amount of charge control agent in the toner) The quantitative determination of the charge control agent was carried out by using the absorbance method. Dissolve a charge control agent such as nigrosine in chloroform,
0.15, 0.76, 1.52, 2.28 and 3.0
Five kinds of samples of 4 mg / 100 ml were prepared, and the absorptiometer UV-1200 (manufactured by Shimadzu Corporation) was used.
When the absorbance at 76 nm was measured, each was 0.0
46, 0.258, 0.522, 0.787 and 1.
A value of 053 was obtained. When the absorbance was plotted on the vertical axis and the concentration of the charge control agent was plotted on the horizontal axis, this was plotted, and the relationship between the absorbance value and the concentration of the charge control agent was a straight line (see FIG. 2). Using this straight line as a calibration curve, the value obtained by measuring the supernatant of the solution of the toner ground product dissolved in chloroform with the absorptiometer was applied to this calibration curve to determine the amount of the charge control agent in the toner. It was quantified. Also,
Considering that the charge control agent is exposed to a high temperature during the manufacturing process, a test in which the charge control agent was heated to 200 ° C. was also conducted, and it was confirmed that this measurement method is effective.

For measuring the distribution of the charge control agent in the toner, a relative dielectric constant measuring method, an alternating current resistance measuring method, a dielectric loss measuring method and the like can be considered, but all of them are influenced by a magnetic substance such as magnetite. Therefore, it was not suitable as a standard measurement method.

(Determination of amount of magnetic substance in toner) The amount of magnetic substance was determined by treating the toner powder to be tested with a "crucible" and burning all organic substances to leave the remaining ash as a magnetic substance. Since the magnetic substance is oxidized by heat, the amount of the magnetic substance was calculated from the corrected value. For example, looking at magnetite, magnetite is oxidized by heat to become trivalent iron oxide (hematite).
The value obtained by multiplying the ash weight by the molecular weight ratio of both, 0.967, was taken as the magnetite magnetic substance amount.

Reference Example (Production of Toner by Conventional Method and Measurement of Distributivity in Each Step of This Production) Thermoplastic Resin (Styrene / Acrylic Resin), Wax (Polypropylene), Charge Control Agent (Nigrosine Dye)
And 56.5% by weight of magnetic material (magnetite),
Used in an amount of 2.0% by weight, 1.5% by weight and 40.0% by weight, and after mixing them well as powders with a mixer,
The mixture was heated and kneaded by a kneader, cooled, coarsely pulverized, and then finely pulverized, and particles having a desired particle size range were classified and taken out to obtain a toner. Using the above measurement method, the distributability of the four raw materials was measured for the pre-mixture (premix), the coarsely crushed chips after discharge from the kneader, the pulverized product, the classified toner (toner of desired particle size), and the classified fine powder. The results are shown in Table 1.

[0035]

[Table 1]

The waxes and charge control agents (CC
The values in each step of A) are shown as bar graphs in FIGS. It can be seen from FIGS. 3 and 4 and Table 1 that there is a large variation in the dispersibility of the wax and the charge control agent in each step.

The mixing ratio of the materials, the order of mixing the materials,
The toner was manufactured by changing various conditions such as the type of mixing or kneading machine, kneading conditions (testing and kneading temperature by kneading machine having multiple screw shapes), cooling method immediately after kneading, cooling temperature, etc. No improvement in variability was observed.

[0038]

EXAMPLES Next, the magnetic toner of the present invention and the method for producing the magnetic toner will be described with reference to the following examples. However, the following examples are for explaining the present invention, and the present invention is not limited thereby.

(Example 1) Polypropylene wax (Viscor 550P: manufactured by Sanyo Kasei Co., Ltd.) was weighed so as to be 2% by weight of the toner prescription amount, added to the reaction liquid, and dispersed in fine particles. Coarse particles 2925 of wax-dispersed poly-methacrylic-styrene copolymer synthesized by adding butyl methacrylate and styrene and a polymerization initiator
g and 75 g of a nigrosine dye (Bontron N-07: manufactured by Orient Chemical Co., Ltd.) as a charge control agent were mixed with a 20 L Henschel mixer for 3 minutes and then charged into a twin-screw kneader (PCM-30 manufactured by Ikegai). . The extruded product was cooled at room temperature and then crushed into pellets. Next, 2000 g of magnetite fine powder was added thereto and mixed for 3 minutes with a Henschel mixer. This was heated and kneaded under the same kneading machine and kneading conditions as in the first kneading, and the extruded product was cooled and then crushed by a coarse crusher. Further, this was finely pulverized with a jet mill pulverizer and subsequently subjected to a classifier to separate particles having a particle size distribution of 5 to 9 μm as fine powder for toner.

In the above steps, samples were taken after mixing the materials, crushing, classifying, and from the filter bag. Further, using a classified toner, an image was printed using a commercially available copying machine (NP-4145 manufactured by Canon Inc.), and the transfer residual toner was collected and used as a sample. The distributability of the material of each sample was measured by the above test method. The results are shown in Table 2.

[Table 2]

As is apparent from this table, it is understood that good distributive property was obtained in all the samples.
In addition, as a result of image output by a commercial copying machine (NP-4145 manufactured by Canon Inc.) using the classified toner, excellent image quality stability was observed in any environment of high humidity, normal humidity and low humidity. It had stable performance.

Comparative Example According to the conventional production method, a poly (butyl methacrylate) / styrene copolymer resin crushed product 282 is used.
Polypropylene wax (Viscole 550
P: 100 g of Sanyo Kasei Co., Ltd.) was roughly mixed for 3 minutes with a Henschel mixer in the same manner as in Example 1, and then a nigrosine dye (Bontron N-07:
Orient Chemical Co., Ltd.) (75 g) and magnetite fine powder (2000 g) were added and mixed for 10 minutes with a Henschel mixer, which was put into a biaxial heating kneader and kneaded. The extruded product is cooled at room temperature, then roughly crushed into pellets, finely crushed with a jet mill crusher, introduced into a classifier, and the portion having an average particle size of 5 to 9 μm is taken out as fine powder for toner. It was Then, in the same manner as in Example 1, after the materials were mixed, kneaded, finely pulverized, and a sample was collected from the collected material in the filter bag. Further, as in Example 1, the transfer residual toner of a commercial copying machine was also taken as a sample. The distributability of the material of each sample was measured by the test method described above. The results are shown in Table 3. As is apparent from Table 3, the toner produced by this conventional method did not show good distributability.

[0043]

[Table 3]

(Example 2) 1500 g of recycled toner (transfer residual toner) obtained in the image output test of Example 1 was mixed with magnetite fine powder in the manufacturing process of Example 1, and wax-added resin chips containing charge control agent were mixed. 2100g
A magnetic toner was manufactured in the same manner as in Example 1 except that 1400 g of magnetite fine powder was mixed and used. Table 4 shows the results of measuring the distribution rate in each step. As shown in Table 4, almost the same distribution rate was obtained in all steps, and satisfactory results were obtained. Then, a comparative inspection was carried out in an image output test using a commercially available copying machine as in Example 1, and the image density, fogging, etc. did not cause any problems, and good results were obtained as with the toner of Example 1.

[0045]

[Table 4]

(Example 3) In place of the recycled toner in Example 2, the filter bag trapping toner obtained when the toner is manufactured by the manufacturing method of Example 1 is used in the same amount as in Example 2. A magnetic toner having a desired particle size distribution was manufactured in the same manner as in Example 1. Samples were taken from each step as in Example 1, and the distribution rate of the raw material was measured. The results are shown in Table 5. As is clear from Table 5, the distribution ratio of the raw material of each sample was almost the same as in Example 2. An image output test was conducted using a commercially available copying machine in the same manner as in Example 1, and the same good results as in Example 1 were shown.

[Table 5]

(Embodiment 4) Toners produced by the production method according to the present invention and discarded at the time of toner production and on the market (classified fine powder, toner collected in filter bags, recycled toner due to transfer residue collected in a copying machine) are used. Classified fine powder 500 to check whether all can be used as re-raw materials
g, 500 g of the toner collected in the filter bag, and 500 g of the recycled toner obtained by collecting the transfer residue were mixed with 2100 g of the wax-added resin chip containing the charge control agent and 1400 g of the magnetite fine powder when the magnetite fine powder was mixed in the manufacturing process of Example 1. A magnetic toner was manufactured in the same manner as in Example 1 except that the re-kneading step was performed. The raw material distribution ratio in each step was measured as in each example. The results are shown in Table 6. As is clear from Table 6, in any of the steps, a good distribution rate was obtained as in Examples 1 to 3, and satisfactory results were obtained. Then, an image output test was carried out using a commercially available copying machine as in Example 1. As a result, a clear image without image density and fogging could be obtained as in Example 1.

[0048]

[Table 6]

[0049]

In the toner manufacturing method according to the present invention, since the relative mixing ratio (distribution ratio) of the constituent materials can be transmitted to the final toner as it is, the performance of the toner can be finely controlled according to the developing situation. This is possible, and as compared with the conventional manufacturing method, in which the developing performance of the toner used cannot be quantitatively grasped and is roughly managed, the developing process can be greatly improved. Therefore, it becomes possible to improve image quality problems such as density, transfer rate, and fog on the toner side, and it becomes easy to maintain good image quality of a copying machine or printer.

In the present situation, the same toner is used as the toner for the copying machine all year round. However, since the development by the toner uses static electricity, it is easily affected by humidity in the operating environment and is not used in the rainy season. In the dry season, the image quality changes even if the same toner is used. As a conventional countermeasure, there was only an improvement method for adjusting the charging voltage / current of the copying machine or the printer and the bias voltage in the development, but it is possible to finely adjust the toner constituent components as in the present invention. It is also possible to provide it to users as toner for winter and summer and to manage the copy image quality as always good.

Further, conventionally, it has been customary to use toner peculiar to the type of the copying machine. However, when fine adjustment of the constituent components of the toner becomes possible in the present invention, toner having various constituent constitutions is used. By mixing and using the toner, it becomes possible to easily obtain a toner that can be applied to a copying machine or a printer other than the system, and it is possible to broaden the usage target.

Further, as described above, by adopting the manufacturing method of the present invention, it is possible to reuse the collected or collected toner such as recycled toner and toner collected in the filter bag, thus reducing the toner manufacturing cost and resources. It is possible to obtain effective effects of effective use of and environmental measures.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between polypropylene blending ratio and endothermic amount measured using a differential scanning calorimeter.

FIG. 2 is a graph showing the relationship between the absorbance value and the concentration of a nigrosine dye used as a charge control agent for light at 576 nm, measured using an absorptiometer.

FIG. 3 is a bar graph showing a wax content in a toner kneaded product in each manufacturing step of a conventional manufacturing method.

FIG. 4 is a bar graph showing the content of the charge control agent in the toner kneaded material in each manufacturing step of the conventional manufacturing method.

FIG. 5 is a manufacturing process diagram of a conventional magnetic toner.

FIG. 6 is a manufacturing process diagram of an example of a method for manufacturing a magnetic toner of the present invention.

Continuation of the front page (56) Reference JP-A-4-204543 (JP, A) JP-A-4-237066 (JP, A) JP-A-9-197718 (JP, A) JP-A-9-274336 (JP , A) JP 2-12160 (JP, A) JP 57-211157 (JP, A) JP 6-67454 (JP, A) JP 6-67455 (JP, A) JP 6-75422 (JP, A) JP-A-6-95433 (JP, A) JP-A-6-282100 (JP, A) JP-A-6-266158 (JP, A) JP-A-8-95296 (JP, A) JP-A-8-62892 (JP, A) JP-A-9-274337 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (7)

(57) [Claims] 1. A wax fine particle dispersed thermoplastic resin is heated and kneaded together with a charge control agent, cooled and then roughly crushed.
A method for producing a magnetic toner, characterized in that the crushed material is heated and kneaded again with the magnetic fine powder. 2. The method for producing a magnetic toner according to claim 1, wherein the wax fine particle-dispersed thermoplastic resin is obtained by polymerizing the thermoplastic resin in the presence of the wax resin. A method for producing a magnetic toner, characterized in that 3. A method for producing a magnetic toner according to claim 1 or 2, prior to heating and kneading, magnetic, characterized in that to produce a powder mixture of raw material powder premixed with toner - of Production method. 4. The method for producing a magnetic toner according to any one of claims 1 to 3 and heating the kneaded product of the first crushed product and the magnetic powder is cooled, and classified after pulverization, the predetermined size A method for producing a magnetic toner, which comprises removing coarse powder and / or fine powder out of the range. 5. A method for producing a magnetic toner according to any one of claims 1 to 4, in at least one step to re-heating and kneading process including reheating kneading step, finely trapped during pulverization A method for producing a magnetic toner, which comprises adding and mixing a powder, a classified coarse powder and / or a classified fine powder. 6. The method for producing a magnetic toner according to any one of claims 1 to 5 either of claims 1-5 1
The toner produced by the method for producing a magnetic toner as described in the above item and collected and collected in the cooling step of the copying machine is added and mixed in at least one step up to the reheat kneading step including the reheat kneading step. A method for producing a magnetic toner, comprising: 7. A magnetic toner produced by the production method of the magnetic toner according to any one of claims 1-6.