JP2839935B2 - Manufacturing method of toner - Google Patents

Description

The present invention relates to a method for producing a toner used for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Conventional technology]

In one example of electrophotography, an electrostatic image is formed on a photoreceptor by charging and exposure, and the electrostatic image is developed by a developer containing toner to form a toner image, and then the toner image is transferred. It is transferred to a material and fixed to form a visible image. On the other hand, the toner remaining on the photoconductor without being transferred to the transfer material is cleaned by the cleaning member.

Conventionally, as a method for producing a toner constituting a developer,
Grinding methods are known. In this pulverization method, a step of mechanically mixing a toner component containing a binder resin, a pigment, and other optional additives (mixing step).
And a step of melt-kneading the obtained mixture (melt kneading step), a step of pulverizing the kneaded material (pulverizing step), and a step of classifying the pulverized material (classifying step).

A pigment as a toner component exhibits a function as a colorant, but generally has a problem that the pigment easily aggregates and has poor dispersibility.

If the dispersibility of the pigment is poor, the pigment separates from the toner particles when mixed and stirred with a carrier to frictionally charge the toner, and the triboelectricity of the toner changes, and the separated pigment The surface of the carrier is contaminated by the toner, and as a result, the amount of triboelectricity of the toner becomes unstable,
There is a problem that fogging occurs in the image and contamination due to toner scattering occurs.

Conventionally, in order to improve the dispersibility of the pigment,
A method has been adopted in which the temperature during melt-kneading is lowered, the number of revolutions of the screw of the kneader is increased, and the residence time of the toner component in the kneader is lengthened.

[Problems to be solved by the invention]

However, in the above-described conventional method, since the molecular chain of the binder resin is severely cut, there is a problem that the resulting toner has poor triboelectric charging properties. Also,
In the above conventional method, the dispersibility of the pigment is still insufficient, and it is difficult to reliably prevent fog and toner scattering.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a toner capable of forming an image free of fog and toner scattering for a long time by suppressing the generation of pigment aggregates. It is to provide a manufacturing method.

[Means for solving the problem]

In order to achieve the above object, the present inventors have conducted intensive studies and found that the free pigment present free from the toner particles includes those generated by the pulverizing step and a developer for frictionally charging the toner. Some of the free pigments are caused by the aggregation of the pigments in the kneaded product obtained by melt-kneading. The inventors have found that the addition of specific powders together with toner components and the mechanical mixing of these powders can suppress the generation of pigment aggregates, thereby completing the present invention.

That is, the production method of the present invention is a method for producing a toner having a step of mechanically mixing a toner component containing at least a binder resin and a pigment, a step of melt-kneading, a step of pulverizing, and a step of classification. In the step of mechanically mixing, a powder containing at least a resin and having a volume average particle diameter of 2 to 15 μm (hereinafter, “specific powder”)
) And mechanically mixed with the toner components.

Further, in the above production method, a binder resin in which particles having a particle size in the range of 0.1 to 5 mm are present in a proportion of 90% by weight or more is used, and the addition ratio of a specific powder is set to 100 parts by weight of the binder resin. It is characterized in that the amount is 5 to 30 parts by weight.

According to such a structural feature, the dispersibility of the pigment in the toner component is improved, and the generation of pigment aggregates is sufficiently suppressed. Therefore, there is no free pigment, the triboelectric charging property of the toner itself is stable, no contamination of the carrier occurs, and a good image can be stably formed many times without fogging and toner scattering. The resulting toner is obtained.

Although the reason why such an excellent action is exhibited is not clear, in the present invention, in the step of mechanically mixing, a specific powder is added and mixed together with the toner component, so that the specific powder is Suppressing the aggregation of the pigment, and also exhibiting the function of separating the aggregate of the pigment once formed, and furthermore, the specific powder adheres to the binder resin while the pigment adheres to the surface of the specific powder. It is considered that the main reason is that the effective surface area of the binder resin increases.

By further defining the particle size, mixing ratio, and the like of the specific powder from the relative relationship with the binder resin and the pigment, the above-described function of the specific powder can be remarkably exhibited.

 Hereinafter, the configuration of the present invention will be specifically described.

The toner component used in the present invention contains at least a binder resin and a pigment, and further uses a specific powder as an essential component.

The binder resin is usually used in a granular form,
In the present invention, a granular form in which particles having a particle size in the range of 0.1 to 5 mm are present in a proportion of 90% by weight or more is particularly preferable. According to such a binder resin, the dispersibility of the pigment is remarkably improved by a synergistic action with a specific powder.

The resin material constituting the binder resin is not particularly limited as long as it is a resin generally used as a binder resin for a toner. Specifically, polyester resin,
Styrene / acrylic resin, polyurethane resin, polyamide resin, epoxy resin and the like can be given as typical examples.

The pigment is usually used in a granular form, but in the present invention, a granular form in which the primary particles have a volume average particle size of about 0.01 μm to 1 μm is preferable.

The pigment is not particularly limited as long as it is a pigment generally used as a toner pigment. Specifically, the following can be mentioned.

(Black pigment)

Carbon black [Magenta, red pigment] CI Pigment Red 5 (Permanent Carmine FB, manufactured by Hoechst Japan) CI Pigment Red 48: 1 (Sumika Print Red C, manufactured by Sumitomo Chemical) CI Pigment Red 53: 1 (Chromoftal Magenta) G, Ciba-Geigy) CI Pigment Red 57: 1 (Sumika Print Carmin 6BC, Sumitomo Chemical) CI Pigment Red 123 (Kayaset Red EB, Nippon Kayaku) CI Pigment Red 139 (Kayaset) Red E-GR, manufactured by Nippon Kayaku Co., Ltd. CI Pigment Red 144 (Chromophtal Red BRN, manufactured by Ciba Geigy) CI Pigment Red 149 (PV Fast Red B, manufactured by Hoechst) CI Pigment Red 166 (Chromoftal) Scarlet R, manufactured by Ciba-Geigy) CI Pigment Red 177 (Chromophthal Red A3B, manufactured by Ciba-Geigy) C I Pigment Red 178 (Kayaset Red E-GG, manufactured by Nippon Kayaku) CI Pigment Red 222 (Chromophthal Red Magenta G, manufactured by Ciba-Geigy) CI Pigment Red 122 (manufactured by Dainippon Ink) Also preferred Commercially available products include KET-Red301, KET-
Red302, KET-Red303, KET-Red304, KET-Red305, KET
-Red306, KET-Red307, KET-Red308, KET-Red309
(Above, manufactured by Dainippon Ink) and PV Fast Red B (manufactured by Hoechst).

(Orange pigment or yellow pigment)

CI Pigment Orange 31 (Chromophtal Orange 4R, Ciba-Geigy) CI Pigment Orange 43 (Hosta Palm Orange GR, Hoechst) CI Pigment Yellow 17 (Fast Yellow GBFN, Sumitomo Chemical) CI Pigment Yellow 14 ( Benzidine Yellow OT, manufactured by DuPont) CI Pigment Yellow 138 (Palio Tol Yellow LO96OHD, manufactured by Bashu) CI Pigment Yellow 93 (Chromoftal Yellow 3G, manufactured by Ciba Geigy) CI Pigment Yellow 94 (Chromophtal Yellow 6G, Ciba Geigy) or a preferred commercially available yellow pigment is KE
T-Yellow401, KET-Yellow402, KET-Yellow403, KET
-Yellow404, KET-Yellow405, and KET-Yellow406 (all manufactured by Dainippon Ink and Chemicals) and the like. Preferred commercially available orange pigments include KET-Orange 501
(Manufactured by Dainippon Ink and Chemicals, Inc.).

(Green pigment or cyan pigment)

CI Pigment Green 7 (Chromoftal Green GF, manufactured by Ciba Geigy) CI Pigment Green 15: 3 (Carmine Blue GNR-O, manufactured by Sumitomo Chemical) CI Pigment Blue 60 (Chromophthal Blue A3R, Ciba Geigy) Preferred commercially available cyan pigments include KET-B
lue101, KET-Blue102, KET-Blue103, KET-Blue104,
KET-Blue105, KET-Blue106, KET-BlueEx-1 (above, manufactured by Dainippon Ink), Heliogen Blue D7080 (BASF
And the like). Preferred commercial products of the green pigment include KET-Green 201 (manufactured by Dainippon Ink and Chemicals).

The content ratio of the above colorant is preferably in the range of 0.5 to 15% by weight based on the toner.

Specific powder used as an essential component in the present invention,
Contains at least resin and has a volume average particle size of 2 to 15μ
m. When the volume average particle size is in this range, the specific powder is well dispersed in the binder resin, and the pigment is well adhered to the surface of the specific powder and sufficiently dispersed. On the other hand, when the volume average particle size exceeds 15 μm, dispersibility in the binder resin becomes poor. On the other hand, when the volume average particle size is 2 μm or less, it is considered that the adhesion of the pigment to the specific powder becomes insufficient, and as a result, aggregates of the pigment are generated, and the dispersibility of the pigment is deteriorated.

Here, the volume average particle size is a value measured by a laser diffraction type particle size distribution analyzer “HELOS” (sold by JEOL Ltd.).

The specific powder may be composed of only a resin, or may contain, in addition to the resin, a substance usually used as a toner component, for example, a pigment, a charge control agent, a wax, or the like.

Examples of the wax include polyolefin wax such as low molecular weight polypropylene and polyethylene, paraffin wax, fatty acid ester wax, and fatty acid amide wax. The fixing property of the toner can be improved by adding the wax.

When a color toner is obtained, a colorless or white charge control agent is preferable so as not to impair the color developing properties of the color toner. Specifically, nigrosine,
Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.), Bontron S-34, E-82, E-87 (above,
Orient Chemical Industry Co., Ltd.). The content of these charge control agents is preferably from 0.4 to 5% by weight based on the toner.

In the present invention, the toner component and the specific powder are used as a toner material, and these are mechanically mixed together to perform the mixing step.

The mixing ratio of the specific powder is preferably in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin constituting the toner component from the viewpoint of sufficiently exhibiting the function of the specific powder. When the mixing ratio of the specific powder is too small, the function of the specific powder is not sufficiently exhibited. On the other hand, when the mixing ratio of the specific powder is excessive, the powder is not adhered to the resin surface but is present in a free state, and is not sufficiently dispersed at the time of kneading.

The mixing ratio of the pigment is preferably in the range of 2 to 20 parts by weight based on 100 parts by weight of the binder resin.

This mixing step may be performed under normal conditions using a normal mixer, and there is no particular limitation.

After the above mixing step is completed, the mixture is then charged into a kneader and melt-kneaded. As the melt kneader, for example, "PCM-45" (manufactured by Ikegai Iron Works) can be used.

It is important that the melt-kneading be performed under appropriate conditions so as not to cause the molecular chains of the binder resin to be cut. Specifically, the melting and kneading temperature determines the softening point of the binder resin.
When the tsp, C ₃ temperature preferably in the range of Tsp-50 ℃ ~Tsp-10 ℃ . When "PCM-45" is used, the screw rotation speed is preferably in the range of 100 to 300 rpm. The discharge rate is preferably in the range of 20 to 50 kg / hour.

After the completion of the above-described melt-kneading step, the kneaded material is then pulverized. In this pulverization step, it is preferable to first perform coarse pulverization and then finely pulverize.

After the pulverizing step is completed or the pulverized product is classified, a toner having a predetermined particle size, for example, an average particle size of 5 to 20 μm is produced.

The toner produced according to the present invention may be a two-component toner mixed with a carrier or a one-component toner that does not require a carrier. When producing a one-component toner, a magnetic powder is usually added as a toner component.

Further, in the bond for preparing the developer, inorganic particles such as hydrophobic silica fine powder may be further added to the toner produced as described above in order to increase the fluidity of the toner.

〔Example〕

Hereinafter, examples of the present invention will be described together with comparative examples, but embodiments of the present invention are not limited to these examples. In the following, “parts” means “parts by weight”.

[Powder] Polyester resin (2mm pass product) 100 parts Polypropylene wax (fine particles) 3 parts Carbon black (fine particles) 10 parts The above materials are mechanically mixed, melt-kneaded, coarsely ground, and then finely ground. And classified, and the volume average particle size is 7 μm
Was produced. This is a powder.

[Powder] A powder having a volume average particle diameter of 11 μm was produced in the same manner as the powder. This is a powder.

[Powder] A powder having a volume average particle size of 15 μm was produced in the same manner as the powder. This is a powder.

[Powder] Volume average particle size consisting of polyester resin alone is 15 μm
The powder is made into powder.

[Powder] In the production of a powder, a powder (volume average particle size of 100 μm) after coarse pulverization but before fine pulverization is used as powder.

[Powder] A powder having a volume average particle diameter of 20 μm was produced in the same manner as the powder. This is a powder.

<Example 1> Polyester resin (2mm pass product) 100 parts Polypropylene wax (fine particles) 3 parts Carbon black (fine particles) 10 parts Powder (volume average particle diameter 7 μm) 20 parts The above materials are mechanically mixed. did. Next, "PCM-4
5 "(manufactured by Ikegai Iron Works) and melt-kneaded at a temperature 10 ° C. lower than the softening point of the polyester resin under the conditions of a screw rotation speed of 150 rpm and a discharge rate of 35 kg / hour. After cooling, pulverize,
After classification, a toner A having a volume average particle diameter of 12 μm was produced.

<Example 2> Toner B was prepared in the same manner as in Example 1 except that the powder was changed to 10 parts of the above powder (volume average particle diameter: 11 µm).
Was manufactured.

<Example 3> Toner C was prepared in the same manner as in Example 1 except that the powder was changed to 5 parts of the above powder (volume average particle size: 15 µm).
Was manufactured.

<Example 4> Toner D was prepared in the same manner as in Example 1 except that the powder was changed to 5 parts of the above powder (volume average particle size: 15 µm).
Was manufactured.

<Example 5> A toner E was produced in the same manner as in Example 3, except that 10 parts of carbon black was changed to 5 parts of copper phthalocyanine.

Comparative Example 1 Comparative toner a was manufactured in the same manner as in Example 1 except that the powder was omitted.

Comparative Example 2 Comparative toner b was prepared in the same manner as in Example 2, except that the powder was removed, the melt-kneading temperature was changed to a temperature lower by 30 ° C. than the softening point of the polyester resin, and the screw rotation speed was changed to 200 rpm. Manufactured.

Comparative Example 3 Comparative toner c was manufactured in the same manner as in Example 1, except that the powder was changed to the above powder.

Comparative Example 4 Comparative toner d was manufactured in the same manner as in Example 1 except that the powder was changed to the above-mentioned powder.

[Evaluation]

<Dispersibility of Pigment> In the above Examples and Comparative Examples, a mass or plate-like kneaded material obtained by melt-kneading was cut into thin pieces having a thickness of 5000 mm, and a cross section of 100 × 100 μm was observed with a transmission electron microscope. Five regions were arbitrarily selected, and pigment aggregates having a cross-sectional area of 20 μm ² or more were counted and converted to the number per 1 mm ² for evaluation.

<Fog and toner scattering> Using the toners obtained in the above Examples and Comparative Examples, a real-image test was performed by an image forming apparatus “Konica 8010” (manufactured by Konica Corporation), and the number of copies reached 30,000. At this point, the occurrence of fog and toner scattering was visually determined.

The above results are shown in Table 1 below. In Table 1,
“○” indicates good, “△” indicates that it is slightly defective but practical, and “×” indicates that it is defective and impractical.

As can be seen from Table 1, it is clear that according to the production method of the present invention, a toner having good pigment dispersibility can be produced. Further, according to the toner manufactured by the manufacturing method of the present invention, it is apparent that a good image can be stably formed many times without fogging and toner scattering.

On the other hand, it is clear that the dispersibility of the pigment is inferior in the production method of the comparative example. In addition, it is apparent that fog and toner scattering easily occur in the toner manufactured by the manufacturing method of the comparative example, and the durability is inferior.

〔The invention's effect〕

As described in detail above, according to the manufacturing method of the present invention, unlike the normal toner manufacturing method, a step of adding a powder having a specific range of the average particle diameter as the toner material, and thus relatively mixing the toner material In, the pigment is not aggregated by the presence of the powder, and the dispersibility is significantly improved.

Accordingly, no pigment is liberated even in the finally obtained toner, and there is no risk that the pigment will be detached from the toner even when a mechanical stirring force is applied to frictionally charge the toner in the developing process.

As a result, good properties of the toner are stably exhibited over a long period of time, and the surface of the carrier is not contaminated by the pigment, so that the durability of the developer is significantly improved.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mayumi Tanaka 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A method for producing a toner comprising: a step of mechanically mixing a toner component containing at least a binder resin and a pigment; a step of melt-kneading; a step of pulverizing; and a step of classifying. A step of adding a powder containing at least a resin and having a volume average particle diameter of 2 to 15 μm, and mechanically mixing with a toner component. 2. The method according to claim 1, wherein 90% by weight of particles having a particle size in the range of 0.1 to 5 mm are used as the binder resin.
A method for producing a toner, characterized in that the powder present in the above ratio is used, and the addition ratio of the powder is 5 to 30 parts by weight based on 100 parts by weight of the binder resin.