JPH03185459A - Color toner and production thereof - Google Patents

Abstract

PURPOSE:To enhance the offset resistance and wrap resistance of the toner and to stabilize a tribo-electricity by incorporating a pigment and a processed pigment formed by kneading a resin for processing which is the same kind of a binder resin into the toner. CONSTITUTION:This toner is formed by incorporating the binder resin (A), polyolefin wax (B) and the processed pigment. The processed pigment is formed by kneading the pigment (C) and the resin (D) for processing which is the same kind of component A. A magenta pigment contg. 2, 9-dimethyl quinacridone is used for the component C. The same kind of the polyester is usable for the components A, D. Polypropylene wax, etc., are usable for the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color toner used for forming a color image and a method for producing the same, and more particularly relates to a color toner using a specific processed pigment and a method for producing the same. .

[Conventional technology]

When a color image is formed by superimposing color toner images by the subtractive color mixing method, color toners such as yellow, magenta, and cyan are used.

In such color toners, pigments are advantageously used as coloring agents from the viewpoint of improving light fastness, color tone, etc. In particular, 2,9-dimethylquinacridone is used as a pigment for magenta toners in terms of color tone. Are suitable.

On the other hand, in order to properly fix the color toner with a hot roller fixing device which is preferable as a fixing means, the color toner needs to have excellent offset resistance and wrapping resistance. From this point of view, it is effective to include polyolefin wax in the color toner.

However, pigments are generally compatible with polyolefin waxes, and 2,9-dimethylquinacridone in particular is extremely compatible with polyolefin waxes, and the polyolefin waxes become finely dispersed together with the pigments in the binder resin, resulting in a magenta toner. During fixing, the polyolefin wax oozes out from the surface of the magenta toner particles insufficiently, resulting in a problem of decreased offset resistance and wrapping resistance.

However, recently, a color toner has been proposed in which a processed pigment coated with a polyester resin having a higher molecular weight than the polyester resin is dispersed in a binder resin made of a polyester resin (Japanese Patent Laid-Open No. 62-28075).
(See Publication No. 5).

[Problems to be Solved by the Invention] However, this technique has the following problems because there is a large difference in molecular weight between the polyester resin that is the binder resin and the polyester resin that is the processing resin.

(1) Toner is generally manufactured through the processes of kneading, pulverization, and classification. During the pulverization process, the contaminants are usually broken from the interface between the binder resin and the polyolefin wax, and the polyolefin wax is formed on the surface of the mixture. Exposed powder particles are obtained. However, in the above technology, since the compatibility between the polyester resins is not sufficient, the polyester resins tend to crack at the interface during the pulverization process, and as a result, it is difficult for polyolefin wax to appear on the surface of the particles obtained by pulverization. , there is a problem that offset resistance and winding resistance deteriorate.

(2) Due to the large difference in molecular weight between the processing resin and the binder resin, the difference in triboelectrification between the two tends to become apparent in the toner particles.As a result, the triboelectrification of the color toner becomes unstable, causing fogging and other problems. There is a problem of toner scattering.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to exhibit excellent anti-offset properties and anti-wrapping properties, as well as stable triboelectric charging properties to prevent fogging and toner scattering. An object of the present invention is to provide a color toner that can improve images without causing the occurrence of color toner, and a method for producing the same.

[Means to solve the problem]

In order to achieve the above object, the color toner of the present invention contains a binder resin, a polyolefin wax, and a processed pigment, and the processed pigment contains a pigment and a processing resin of the same type as the binder resin. A composition obtained by kneading is adopted.

The method for producing a color toner of the present invention includes the steps of mechanically mixing a binder resin, a polyolefin wax, and a processed pigment, melt-kneading, and pulverizing the processed i.
As the material I, a material obtained by kneading a pigment and a processing resin of the same type as the binder resin is used.

That is, the present invention provides a method for forming a color toner using a binder resin, a polyolefin wax, and a pigment. By using a pigment, the dispersibility of the processed pigment in the binder resin is improved and the chance of contact between the pigment in the processed pigment and the polyolefin wax is reduced, which results in fine dispersion of the polyolefin wax in the binder resin. By avoiding this, the polyolefin wax sufficiently oozes out from the surface of the toner particles during hot roller fixing, dramatically improving offset resistance and wrapping resistance. This prevents the triboelectric charging properties of the color toner from being inhibited by the processing resin, stabilizes the triboelectric charging properties of the color toner as a whole, and prevents fogging and toner scattering. .

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

The processed pigment used in the present invention is obtained by kneading the pigment and a processing resin of the same type as the binder resin.

As a pigment, it has excellent light resistance, color tone, etc.
A magenta pigment (hereinafter sometimes referred to as "specific magenta pigment") containing 2,9-dimethylquinacridone is used. This particular magenta pigment is particularly compatible with polyolefin wax, which tends to cause the polyolefin wax to bleed out insufficiently, but in the present invention, it is used in the form of a processed pigment using a specific processing resin. Therefore, the polyolefin wax bleeds out sufficiently, and a magenta toner exhibiting excellent anti-offset and anti-wrapping properties can be obtained.

As the processing resin, the same type of resin as the binder resin is used, but this "same type" does not mean only when the binder resin and the processing resin are completely the same, but also when the types of both resins are the same. In addition, when the weight average molecular weight of the binder resin is A1 and the weight average molecular weight of the processing resin is B, the more the ratio A/B is in the range of 0.7 to 1.3, the closer the weight average molecular weights of both are. It means to be there.

Moreover, "weight average molecular weight" refers to the weight average molecular weight measured by gel permeation chromatography (GPC) as follows.

At a temperature of 40°C, the solvent (tetrahydrofuran) was flowed at a flow rate of 1.2-min/min, and the concentration was 0.2 g/2011.
11 tetrahydrofuran sample solution as sample weight 3
Inject mg and measure the molecular weight. When measuring the molecular weight of a sample, select measurement conditions in which the molecular weight of the sample falls within a range in which the logarithm of the molecular weight and the count number of a calibration curve created using several types of monodispersed polystyrene standard samples form a straight line. The reliability of the measurement results is that when the molecular weight of the NB5706 polystyrene standard sample is measured under the above conditions, the weight average molecular weight of the standard sample is 28.8X10.
It can be confirmed by '. Also, G
A PC column that satisfies the above conditions is used, specifically TSK-GEL manufactured by Toyo Soda.
SGMHs etc. can be used. Note that the solvent and measurement temperature are not limited to the above conditions, and may be changed as appropriate.

Such processing resins and binder resins can be selected from resins such as polyester resins, styrene resins, acrylic resins, styrene-acrylic copolymer resins, and epoxy resins.

In particular, polyester resin can be preferably used since frictional charging can be easily controlled. This polyester resin is a resin obtained by polycondensing polycarboxylic acid and polyol.

In the processed pigment, the mixing ratio of the processing resin and the pigment is about 20 to 300 parts by weight of the pigment to 100 parts by weight of the processing resin. Further, the proportion of pigment in the entire color toner is about 1 to 20% by weight.

As a method for producing processed pigments, for example, a granular or powdery processing resin and a granular or powdery pigment are mixed, melted and kneaded, then cooled and pulverized, thereby producing a granular or powdery processed pigment. You can adopt a method to obtain

As the polyolefin wax, polyethylene wax, polypropylene wax, etc. can be used.

Further, the color toner of the present invention may contain other toner components as necessary.

Next, a method for producing color toner of the present invention will be explained.

The production method of the present invention includes a step of mechanically mixing, melt-kneading, and pulverizing a binder resin, a polyolefin wax, and a processed iia, and as the processed pigment, the pigment and the same kind as the binder resin are used. The one obtained by kneading with the processing resin is used.

Specifically, the binder resin, polyolefin wax, the above-mentioned specific processed pigment, and other components used as needed are mechanically mixed using a Henschel mixer or the like to uniformly disperse the materials. Next, these are heated using an extruder or the like to thoroughly melt and knead them. Thereafter, it is cooled, coarsely pulverized, further finely pulverized, and then classified to produce a color toner having a predetermined particle size distribution.

〔Example〕

Examples of the present invention will be described below along with comparative examples, but the present invention is not limited to these embodiments. In addition,
In the following, "parts" represent "parts by weight."

Example 1 <Production of processed pigment> Processing resin 60 parts (polyester resin with weight average molecular weight 11Mw of 110.000) Pigment 40 parts (2,9-
Magenta Pigment Containing Dimethylquinacridone) The above-mentioned materials were melt-kneaded using a pressurized niegu to obtain a pelletized processed pigment Ml.

<Manufacture of color toner> Binder resin 94 parts (polyester resin same as the above processing resin with weight average molecular weight Mw of 110.000) Polypropylene wax 2 parts Processed pigment M1 10 parts or more of the above materials were mechanically mixed using a Henschel mixer. After mixing, the mixture is melt-kneaded using an extruder and then pulverized until the average particle size is approximately 13.
A magenta color toner T1 of p1 was obtained.

Example 2 A magenta color toner T2 was obtained in the same manner as in Example 1 except that the binder resin was changed to a polyester resin having a weight average molecular weight Mw of 80.000.

Example 3 Magenta color toner T3 was obtained in the same manner as in Example 1 except that the binder resin was changed to a polyester resin having a weight average molecular weight Mw of 140.000.

Example 4 Magenta color toner T4 was obtained in the same manner as in Example 1 except that polypropylene wax was changed to polyethylene wax.

Comparative Example 1 Binder resin 100 parts (polyester resin with a weight average molecular weight Mw of 110.000) Polypropylene wax 2 parts Pigment
4 parts (magenta pigment containing 2,9-dimethylquinacridone) The above materials were mechanically mixed using a Henschel mixer, then melted and kneaded using an extruder, and then pulverized to produce magenta with an average particle size of about 13 pm. Color toner t1 for use was obtained.

Comparative Example 2 Manufacture of processed pigment> Processing resin 60 parts (polyester resin having a weight average molecular weight Mw of 85.000) Pigment 40 parts (2,9-
Magenta Pigment Containing Dimethylquinacridone) The above materials were melt-kneaded using a pressurized niegu to obtain ml of pelletized processed pigment.

<Manufacture of color toner> Binder resin 94 M (polyester resin with weight average molecular weight Mw of 7.200) Polypropylene wax 21S Processed pigment ml 10 parts or more of the materials were mechanically mixed using a Henschel mixer, and then melted using an extruder. After kneading, the mixture was pulverized to obtain magenta comparative color toner t2 having an average particle size of about 13 pm.

Comparative Example 3 A comparative magenta color toner t3 was obtained in the same manner as in Comparative Example 1 except that polypropylene wax was changed to polyethylene wax.

<Evaluation Test> Two-component developers were prepared by mixing each of the color toners obtained in the above Examples and Comparative Examples with a carrier at a ratio such that the toner concentration was 7% by weight. The carrier used was made of styrene/methyl methacrylate copolymer resin and had a thickness of 1.5 mm on the surface of spherical ferrite particles. This is a coated carrier having a weight average particle size of 30IjIl and provided with a resin coating layer of On.

<1> Offset resistance and wrapping resistance Using each of the above two-component developers, a width of 5 mm was
A test was conducted in which a solid unfixed toner image of cm was formed, and then this unfixed toner image was fixed from the leading side of the fixing paper using a heat roller fixing device by changing the design temperature of the heat roller, and the offset occurrence temperature and The temperature at which winding occurs was determined.

The upper limit of the set temperature of the heat roller is 240℃, and the lower limit is 1
The temperature was 50°C.

Mako, this heat roller fixing device uses an oil-less heat roll system that does not apply silicone oil to the roller, and the surface layer of the upper roller is made of PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer). The surface layer of the lower roller is made of silicone rubber. In addition, the load on the upper roller is 1.5 kg/cm,
The linear speed was set at 140 mm/sec.

(2) Fog and toner scattering Using each of the above two-component developers, a test was conducted in which copy images were continuously formed 10,000 times using an image forming apparatus rDC-8010J (manufactured by Konica). Fog and toner scattering after 000 cycles were evaluated as follows.

■Measure the relative density of the white background in the copy image using a fogging "Sakura Densitometer" (manufactured by Konica), and if the relative density is less than 0.01, it is judged as "○J, 0.01 or more".
A case of less than 3 was given as "ΔJ", and a case of 0.03 or more was given as "x".

■Toner scattering When visually observing the inside of the image forming device, "O" indicates that almost no toner scattering is observed, "Δ" indicates that some toner scattering is observed but at a practical level, and "Δ" indicates that there is considerable toner scattering. If this occurs and there is a problem in practical use, mark it with “×”
−.

The results are shown in Table 1.

As is clear from the results in Table 1, the color toners Tl to T4 of the present invention contain a binder resin, a polyolefin wax, and a processed pigment, and the processed pigment contains a pigment and a binder resin. Because it is obtained by kneading the same type of processing resin, it exhibits excellent anti-offset and anti-wrapping properties, as well as stable triboelectric charging properties to prevent fogging and toner scattering. It can be prevented.

On the other hand, in the color toners t1 and t3 of Comparative Example 1, since the pigment was directly dispersed and contained in the binder resin together with the polyolefin wax, the polyolefin wax did not ooze out sufficiently and the curling resistance and offset resistance were insufficient. Both genders are inferior.

In the color toner of Comparative Example 2, fogging and toner scattering occurred because the processing resin was a polyester resin having a higher molecular weight than the polyester resin that was the binder resin.

Moreover, according to the color toners Tl to T4 of the present invention, magenta images with excellent durability and color tone were obtained.

〔Effect of the invention〕

According to the invention of claim 1, since it contains a binder resin, a polyolefin wax, and a processed pigment using the same type of resin as the binder resin as a processing resin, fine dispersion of the polyolefin wax is suppressed. This allows for sufficient bleeding during fixing, resulting in excellent anti-offset and anti-wrapping properties, as well as stable tribo-charging properties without the risk of the tribo-charging properties of the color toner being inhibited by the processing resin. This prevents fogging and toner scattering.

According to the second aspect of the invention, excellent anti-offset properties and anti-wrapping properties can be obtained even when a magenta pigment containing 2,9-dimethylquinacridone, which is particularly compatible with polyolefin wax, is used.

According to the third aspect of the invention, since the binder resin and the processing resin are the same type of polyester resin, it is easy to control triboelectricity, and the occurrence of fogging and toner scattering can be more effectively prevented. The offset property and the winding resistance are also improved.

According to the invention of claim 4, the step of mechanically mixing, melt-kneading, and pulverizing a binder resin, a polyolefin wax, and a processed pigment using the same type of resin as the binder resin as a processing resin is performed. As a result, it is possible to produce a color toner that not only exhibits excellent anti-offset properties and anti-wrapping properties, but also can form images without fogging or toner scattering.

Claims (4)

[Claims] (1) Binder resin, polyolefin wax,
A color toner comprising a processed pigment, wherein the processed pigment is obtained by kneading a pigment and a processing resin of the same type as the binder resin. (2) The color toner according to claim 1, wherein at least the pigment is a magenta pigment containing 2,9-dimethylquinacridone. (3) Claim 1 or 2, wherein the binder resin and the processing resin are the same type of polyester resin.
Color toner described in . (4) Binder resin, polyolefin wax,
The process includes mechanically mixing, melt-kneading, and pulverizing the processed pigment, and the processed pigment is obtained by kneading the pigment and a processing resin of the same type as the binder resin. Characteristic color toner manufacturing method.