JPH09288379A - Production of color toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure high color development property and a wide color reproduction region of a full-color image, to improve the durability of a color toner by finely dispersing pigment in a colorant and to attain high transparency on an OHP sheet. SOLUTION: This color toner consisting essentially of a colorant and a bonding resin is produced through a 1st process in which a 1st bonding resin is kneaded with a wet pigment having 40-80wt.% water content by means of a vertical shaft type high-speed kneader with multistage blades or multistage stirring blades, the water is removed, and a 2nd process knading the resultant colorant with a 2nd bonding resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing color toner.

[0002]

2. Description of the Related Art In recent years, an electrostatic charge image of an original is formed by exposing it to light that has been dispersed, and then developed with three color toners (or four colors including black), and color superposition is performed to form a full color image. The obtained full-color copying method has been put into practical use, and the development of copying machines using this method has been brisk. As such colorants, organic pigment-based colorants are used from the viewpoint of light resistance, safety and the like.

However, the organic pigment-based coloring agent has a drawback that when it is in a dry powder state, it is difficult to disperse it in the binder resin used for the toner, and the organic pigment exists as an aggregate. Full-color toners are often applied to OHP (overhead projector) sheets, and are strongly required to have light transmittance. However, during full-color toner,
If the organic pigments described above are present as agglomerates, there are problems that the light transmittance, which is an important characteristic, is deteriorated, and the color reproducibility is deteriorated.

As a method for improving the dispersion of the organic pigment in the toner, Japanese Patent Laid-Open No. 62-127847 discloses a method for producing a blue toner. This method is a flushing method in which a water-containing paste of an α-phthalocyanine pigment and a solution of a binder resin in an organic solvent are heated and mixed to remove water and the organic solvent. (The colorant obtained by this method is referred to as a flushing pigment.) The light transmittance and color reproducibility of the toner produced by using the flushing pigment obtained by this method are considerably improved as compared with the toner by the conventional method. There is.

However, the α-type phthalocyanine crystal used here is liable to cause crystal growth and transition due to the unstable crystal type, and is apt to cause a decrease in coloring power and a change in hue, and a cyan toner for full-color toner. Is not preferred, and β-type phthalocyanine crystals are preferably used. Further, this method cannot be applied to yellow pigments and magenta pigments that do not rely on this method because it is a limited method such as the acid paste method and the acid slurry method. Further, this method uses an organic solvent when substituting the water in the water-containing paste, but it is difficult to recover the solvent, which is not preferable in terms of environmental hygiene. Furthermore, when the organic solvent solution of the binder resin and the water-containing paste of the pigment are mixed, since they are mixed with a kneader for kneading a high-viscosity material, suitable shear stress is not applied and pigment dispersion becomes insufficient, resulting in high concentration. It is difficult to obtain a colorant containing a pigment, and the flushing pigment becomes dough-like (dough: a soft lump-like, showing a dango state), the efficiency of the vacuum dehydration is poor, and the dehydration takes a lot of time. There's a problem.

Further, in the method described in JP-A-4-2427, a water-containing paste of an organic pigment is heated together with a binder resin, heated and mixed in a pressure kneader at a temperature of at least 100 ° C. or higher, and water is melted by the molten resin. It is stated that the unit of pigment dispersion in the toner can be controlled by producing a colorant in which the organic pigment is dispersed at a high concentration (hereinafter referred to as a melt flushing pigment) by removing and replacing it into a toner. .

However, in this case as well, JP-A-62-1
Since a pressure kneader for high-viscosity kneading is used as in the case of Japanese Patent No. 27847, when the resin is melted by heating at 100 ° C. or higher and the mixture has a low viscosity, shearing suitable for loosening pigment aggregates is performed. It is not preferable because stress is not applied, and the pigment particles become insufficiently dispersed mainly due to the action of wetting the binder resin to the pigment particles rather than the action of dispersing the pigment particles. Furthermore, the water content of the wet pigment evaporates and is lost by heating at 100 ° C. or higher, increasing the aggregates of the pigment,
It is not preferable because the pigment is dispersed in the resin in an insufficiently dispersed state.

When a pressure kneader having a large maximum power consumption is used, excessive power consumption is required to obtain the final melt flushing pigment, and the melt flushing pigment becomes dough-like and is heated at 100 ° C. or higher. However, the dehydration efficiency is poor, and it takes a lot of time for dehydration, which is a problem.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 7-261460 prevents the change in molecular weight by using a linear polyester as a pigment-dispersing resin, but it is still unsuitable for fine dispersion treatment of pigments. Since the kneader is used, the dispersion of the pigment is insufficient, and the production efficiency is poor and there is a problem.

[0010]

SUMMARY OF THE INVENTION The present invention has been made as a result of the inventors' own studies in view of the above problems. That is, the object of the present invention is to achieve high color development of a full-color image and a wide color reproduction range, and to enhance the durability of the color toner by finely dispersing the pigment in the colorant, and to achieve high light transmission on the OHP sheet. It is to provide a color toner capable of exhibiting properties.

[0011]

A first invention is a method for producing a color toner comprising at least a colorant and a binder resin, which is a wet pigment having a first binder resin and a water content of 40 to 80 wt%. And kneading with a vertical axis type high speed kneader equipped with a multi-stage blade or multi-stage stirring blade, a first step of removing water, and a second step of kneading the obtained colorant with a second binder resin. It is a method of manufacturing a color toner, which is characterized by passing through steps.

The second invention is such that the kneading temperature in the first step is
The method for producing a color toner according to the first invention is characterized in that the glass transition temperature of the first binder resin is equal to or higher than the glass transition temperature and is substantially lower than 100 ° C.

In a third aspect of the invention, the first binder resin is a linear polyester resin, and the polyester constitutes 2
Of the polyhydric alcohol components, ethylene glycol is contained in an amount of 20 wt% or more of the total alcohol components, glass transition temperature Tg = 65 ° C. or lower, and weight average molecular weight Mw = 5000-2.
0000, Mw / Mn = 3.0 or less, acid value 15 mg KO
H / g or less, which is the method for producing a color toner according to the first invention or the second invention.

In a fourth aspect of the invention, the second binder resin is a non-linear polyester resin, and the weight average molecular weight Mw is 20,000 to 6
10,000, Mw / Mn = 6.0 or more, acid value 15 mg KOH / g
The method for producing a color toner according to any one of the first to third inventions is characterized in that:

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have found that the difference in image quality and durability when used as color toners are deeply related to the pigment dispersion conditions in the colorant manufacturing process. In particular, it has been found that the mechanical shear stress and the heating shear temperature have a great influence on the high dispersion of the pigment in the colorant.

Hereinafter, the present invention will be described in detail. As the high-speed kneader in the present invention, a vertical type having a multistage blade or multistage blade is used. A vertical axis type high-speed kneader equipped with multi-stage blades or multi-stage blades is such that high-speed rotating blades or upper and lower blades continuously apply mechanical shearing force to the agglomerated pigment body to crush it into a shape close to primary pigment particles. 1
Macroscopically, the pigment particles are mechanically driven into the binder resin of
Further, it is adsorbed microscopically, and finally, the pigment particles are transferred to the first binder resin phase by a strong stirring action. Therefore, such a high-speed kneader is suitable for highly dispersing the pigment in the color toner. Thus, it is possible to preferably obtain a color toner having excellent color development and a wide color reproducibility region.

The vertical type high speed kneader equipped with the multi-stage blades or multi-stage blades used in the present invention includes a speed mixer, power kneader, rigid mixer, hybrid mixer, dispersive agitator, twin shaft mixer,
A combimix, a flow jet mixer and the like can be mentioned, but a super mixer (Kawata), a Henschel mixer (Mitsui Mining / Henschel Germany) and the like are preferably selected as typical examples.

[0018]

The wet pigment used as the colorant in the present invention is one which does not dry the pigment produced from the water phase, and it is important that the water content is in the range of 40 to 80 wt%, and particularly preferably. It is preferably in the range of 55 to 75 wt%. Water content of wet pigment is 50wt
When it is less than%, the wettability between the pigment particles and the first binder resin is deteriorated, and the pigment particles are not smoothly transferred to the resin phase, resulting in insufficient pigment dispersion. Further, as the amount of water decreases, the aggregation of pigment particles progresses, so that the dispersed particle size of the pigment becomes large, and again the pigment dispersion becomes insufficient.

On the other hand, the water content of the wet pigment is 80% by weight.
When it becomes larger, a so-called slurry state (a state containing a large amount of water) is formed at the time of kneading with the first binder resin, and suitable mechanical shear stress is not applied, and thus the pigment dispersion is also insufficient.

As the wet pigment having a water content of 40 to 80 wt%, for example, monoazo yellow, disazo yellow,
Carmine, rhodamine, quinacridone, phthalocyanine, anthraquinone, thioindigo, perinone, perylene, dioxazine, quinophthalone, isoindolinone,
Wet pigments such as organic pigments such as benzimidazolone or various pigments such as carbon black can be used. Especially C.I. I. Pigment Red 48: 1, C.I. I.
Pigment Red 122, C.I. I. Pigment Yellow 1
7, C.I. I. Pigment Blue 15: 3 and other wet pigments are preferably used.

In the present invention, the reaggregation of the pigment due to the evaporation of the water content of the wet pigment is prevented, and the water content is kept constant by the circulation of the evaporation and recooling of the water in the closed type kneading machine so that the coloring agent in the tank is colored. In a so-called clay state (in which the water content is further reduced than in the slurry state) and shear stress is applied in an appropriate range, the kneading temperature in the first step is the glass transition of the first binder resin. It is preferable that the temperature is equal to or higher than the temperature (Tg) and substantially lower than 100 ° C., and further, "the glass transition temperature (Tg) of the first binder resin (Tg) +20".
It is preferable to knead in the range of "° C" to 95 ° C.

Glass transition temperature (Tg) of the first binder resin
Good results are obtained by performing shear kneading as described above, because the affinity between the first binder resin and the pigment particles dispersed in the wet pigment is increased by being heated to the glass transition temperature or higher, and the pigment is It is presumed that the particles are smoothly dispersed in the resin. Further, when the kneading temperature is 100 ° C. or higher, this temperature is almost close to the softening temperature of the first binder resin, so that the resin starts to be melted or softened and is fused to the blade, stirring blade, inner wall, etc. of the high speed kneader. Therefore, suitable mechanical shear stress is not applied, resulting in poor dispersion of the pigment and further lowering the production efficiency, which is not preferable.

The glass transition temperature (Tg) of the first binder resin used in the present invention is 50 to 65 ° C., preferably 55.
C. to 60.degree. C. is preferable. When the Tg is in the above range, the first binder resin having a Tg lower than 50 ° C. deteriorates the blocking property of the toner when it is used as a color toner. On the other hand, a resin having a Tg of 65 ° C. or higher has a wide molecular weight distribution, resulting in insufficient pigment dispersion.
The light transmittance of the sheet easily deteriorates.

The first binder resin in the present invention is preferably a linear polyester resin synthesized from a divalent alcohol monomer and a divalent carboxylic acid, and 20 mol% or more of all alcohol monomer components are ethylene. Desirably glycol, more preferably 30 mo
It is preferably in the range of 1% to 60 mol%. In particular, ethylene glycol is used because aliphatic alcohols are alkyl-based and alkenyl-based alcohols act as soft segments compared to aromatic alcohols. Among aliphatic alcohols, the shorter the carbon chain, the stronger the tendency. This is because it exhibits suitable properties for finely dispersing the pigment.

In addition to the above dihydric alcohol monomer components, bisphenol A ethylene oxide adducts, bisphenol A propylene oxide adducts, bisphenol A alkylene oxide adducts and the like are suitable, and glycols other than ethylene glycol are suitable. Is mentioned. The divalent carboxylic acid monomer component is preferably composed of terephthalic acid or isophthalic acid. Other monomers include phthalic acid, fumaric acid, maleic acid and the like.

The linear polyester resin preferably used in the present invention has a weight average molecular weight Mw of from 5,000,000 to.
It is preferably 20,000, more preferably 5,000 to 15,000, and most preferably 7,000 to 12,000. The number average molecular weight Mn of the linear polyester resin is preferably from 10 to 60,000, more preferably from 0.
It is desirable to be in the range of 20,000 to 55,000. Weight average molecular weight is greater than 20,000, or number average molecular weight is 0.6
If it is larger than 10,000, pigment dispersion tends to be insufficient. Also,
If the weight average molecular weight is less than 5,000,000 or the number average molecular weight is less than 0.1000, the glass transition temperature of the first binder resin is lowered, and the blocking property of the toner tends to be deteriorated.

Further, the molecular weight distribution of the linear polyester resin preferable as the first binder resin is important, and in the present invention, in order to highly disperse the pigment particles in a form close to the primary particles, the molecular weight distribution Mw /Mn=3.0 or less is preferable, and Mw / Mn = 2.0 to 2.5 is more preferable. When Mw / Mn = 3.0 is exceeded, the color developability of the toner is insufficient and the light transmittance of the color image of the OHP sheet tends to be poor.

Further, the acid value of the linear polyester resin preferable as the first binder resin in the present invention is 15 mgK.
OH / g or less is preferable, and further 5 to 10 m
It is preferably gKOH / g. If the acid value of the linear polyester resin is larger than 15 mgKOH / g, it tends to absorb water, the water content in the colorant becomes large, and the toner chargeability tends to deteriorate.

The second binder resin in the present invention is preferably a non-linear polyester resin synthesized from a divalent alcohol monomer and a trivalent carboxylic acid.

As the divalent alcohol monomer component,
Examples thereof include bisphenol A ethylene oxide adducts, bisphenol A propylene oxide adducts, bisphenol A alkylene oxide adducts, and the like, and examples of the monomers used together with these monomers include glycols such as ethylene glycol.

Examples of the trivalent carboxylic acid monomer include 1,2,4-benzenetricarboxylic acid, 1,2,5
-Benzenetricarboxylic acid and the like. Also, 3
A divalent carboxylic acid monomer may be used together with the divalent carboxylic acid monomer. Terephthalic acid, isophthalic acid and the like are preferably used as the divalent carboxylic acid monomer.

The weight average molecular weight Mw of the non-linear polyester resin suitable as the second binder resin used in the present invention is preferably 20,000 to 60,000, more preferably 20,000 to.
The number average molecular weight Mn is preferably from 10,000 to 60,000, more preferably from 20,000 to 50,000. When the weight average molecular weight is larger than 60,000 or the number average molecular weight is larger than 60,000, the low temperature fixing property is deteriorated,
If it is small, the offset property of the toner tends to deteriorate.

The softening point of the second binder resin is 80-1.
It is preferably in the range of 30 ° C, preferably 90 to 120 ° C. If the softening point is higher than the above range, the low temperature fixability will be poor, and if it is low, the toner blocking property will be poor. Further, the glass transition point of the binder resin is in the range of 50 to 70 ° C, preferably 55 to 65 ° C.

Further, a preferable non-linear polyester resin as the second binder resin is a molecular weight distribution Mw / Mn = 6.
It is preferably 0 or more, more preferably Mw /
Mn = 7.0-10.0. If it is smaller than Mw / Mn = 6.0, the offset property deteriorates, and Mw / Mn = 1.
When it is 2.0 or more, the low temperature fixability tends to deteriorate.

The acid value of the second binder resin in the present invention is
It is preferably 15 mgKOH / g or less, more preferably 5 to 10 mgKOH / g. Acid value is 1
If it is larger than 5 mgKOH / g, the charging stability at high temperature and high humidity will deteriorate, and it will be difficult to obtain sufficient image quality.

Further, the softening point of the non-linear polyester resin which is preferable as the second binder resin is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. If the softening point is higher than the above range, the low temperature fixability will be poor, and if it is low, the toner blocking property will be poor.
The glass transition temperature of the non-linear polyester resin is 5
It is desirable that the temperature is in the range of 0 to 70 ° C, preferably 55 to 65 ° C.

In the present invention, the weight average molecular weight and the number average molecular weight of both the first binder resin and the second binder resin are commercially available gel permeation chromatography (GP).
C) was used, tetrahydrofuran was used as a solvent, the flow rate was 1.0 ml / min, room temperature, and the detector was determined by a differential refractometer (RI).

In the present invention, Tg of both the first binder resin and the second binder resin is a differential scanning calorimeter DSC200.
/ SSC500 system (manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample weight was about 10 mg, the temperature was raised from room temperature to 200 ° C. at a heating rate of 10 ° C./min, and the value determined by the tangent method from the DSC curve was taken as the glass transition temperature. did.

In the present invention, the acid value of both the first binder resin and the second binder resin was determined by back titration with potassium hydroxide, and the acid value was expressed in mg of KOH per 1 g of binder resin. .

In the present invention, the above organic pigment is subjected to a first step, that is, a mechanical shear mixing treatment with the first binder resin to obtain a colorant. Specifically, it is obtained by adding the first binder resin to the above-mentioned organic pigment wet pigment, transferring the pigment in the wet pigment to the resin while shear-kneading with a high-speed kneader, and removing water. The content of the organic pigment in the colorant is preferably in the range of 20 to 50 wt%.

In the present invention, the colorant which has undergone the first step is
If necessary, the shape of the toner may be adjusted by crushing with three rolls of heat and the like, followed by crushing and classifying through the second step, and various additives may be added to produce a color toner. The colorant is preferably contained in an amount of 1.5 to 15 parts by weight based on 100 parts by weight of the color toner. If the blending amount is less than 1.5 parts by weight, the coloring power becomes weak, and if it is more than 15 parts by weight, the light transmittance of the color toner may be lowered.

In the present invention, a colorless or pale color charge control agent may be added if necessary. A colorless or light-colored charge control agent is a quaternary ammonium salt, and a styrene-acrylic resin C having a sulfonic acid group introduced into the resin
CA, a boron complex, a silicon complex, a chromium complex, a zinc complex, etc. are mentioned. The amount of charge control agent added is preferably in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of the binder. Within the above range, the desired charge amount can be controlled.

Further, in the present invention, a fluidizing agent may be added if necessary. Any metal oxide may be used as long as its surface is hydrophobized, and may be used alone or in combination of two or more kinds. Examples thereof include hydrophobized silicon dioxide particles, hydrophobized titanium oxide particles, hydrophobized aluminum oxide particles, and the like. The addition amount of the fluidizing agent is preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the binder resin. Further, a metal oxide or the like may be added as a resistance adjusting agent. For example, tin-based oxides, zinc-based oxides, etc. may be used, and further, metal oxides whose surface is doped with a conductive substance or whose surface is treated with a metal oxide different from the base material are used. May be.

The color toner obtained by the manufacturing method of the present invention may be pulverized by various methods.
Examples of the pulverization method include jet mill pulverization and mechanical pulverization. Further, the toner particle size is 4 to 11 μ in volume particle size.
It is preferably in the range of m, but by achieving high dispersion of the pigment according to the present invention, it can be suitably used as a so-called small particle size toner of 4 to 8 μm.

[0046]

The present invention will be described in more detail based on the following examples. Colorant manufacturing method-1 First binder resin 100 parts by weight Wet cyan pigment (CI Pigment Blue 15: 3 with a water content of 60%) 250 parts by weight The first binder resin is a divalent alcohol monomer. 40 mol% of ethylene glycol is contained among the components, weight average molecular weight Mw = 10,000, number average molecular weight Mw = 0.450,000,
Mw / Mn = 2.2, glass transition point 60 ° C., softening point temperature 107 ° C., acid value 8.9. Using the Henschel mixer (Mitsui Miike Kakoki), the above components are sheared and kneaded at a kneading temperature of 85 ° C., the pigment is transferred to the first binder resin to remove water, and a cyan colorant a having a pigment content of 50 wt% is obtained. Was produced.

Colorant Production Method-2 Wet Cyan Pigment (CI Pigment Blue 15:
3) 278 parts by weight of wet magenta pigment (water content 6
4 wt% C.I. I. Pigment Red 122),
A magenta colorant b having a pigment content of 50 wt% was produced in the same manner as in the colorant production method-1 except that the kneading temperature was 80 ° C.

Colorant Production Method-3 Wet Cyan Pigment (CI Pigment Blue 15:
3) 303 parts by weight of wet yellow pigment (water content 6
7 wt% C.I. I. Pigment Yellow 17),
A yellow colorant c having a pigment content of 50 wt% was produced in the same manner as in Colorant Production Method-1 except that the kneading temperature was 90 ° C.

Colorant Production Method-4 A super mixer (Kawata) was used instead of the Henschel mixer, and 208 parts by weight of the wet cyan pigment (CI Pigment Blue 15: 3) was added to the wet cyan pigment (water content: 52 wt%). C. I. Pigment Blue 15:
A cyan colorant d having a pigment content of 50 wt% was produced in the same manner as in Colorant production method-1 except that the above method was used instead of 3).

Colorant Manufacturing Method-5 Wet Cyan Pigment (CI Pigment Blue 15:
3) 250 parts by weight of wet magenta pigment (water content 6
0 wt% C.I. I. Pigment Red 122), except that the colorant production method-4 was repeated to prepare a magenta colorant e having a pigment content of 50 wt%.

Colorant Manufacturing Method-6 Wet Cyan Pigment (CI Pigment Blue 15:
3) 455 parts by weight of wet yellow pigment (water content 7
8 wt% C.I. I. Pigment Yellow 17) except that the yellow colorant f having a pigment content of 50 wt% was produced in the same manner as in Colorant Production Method-4.

Colorant Manufacturing Method-7 167 parts by weight of wet cyan pigment (CI Pigment Blue 15: 3 having a water content of 40 wt%) was kneaded at a kneading temperature of 80 ° C. by a pressure kneader (Inoue Seisakusho). A cyan colorant g having a pigment content of 50 wt% was prepared in the same manner as in Colorant production method-1 except for the above.

Colorant Manufacturing Method-8 Wet Cyan Pigment (C.I. Pigment Blue 15:
3) 222 parts by weight of wet magenta pigment (water content 5
5 wt% C.I. I. Pigment Red 122) was used, and Magenta Colorant h having a pigment content of 50 wt% was produced in the same manner as in Colorant Production Method-7.

Colorant Manufacturing Method-9 Wet Cyan Pigment (C.I. Pigment Blue 15:
A yellow colorant i having a pigment content of 50 wt% was obtained in the same manner as in the colorant production method-7, except that 3) was replaced with 1000 parts by weight of a wet yellow pigment (CI pigment yellow 17 having a water content of 90 wt%). Was produced.

Colorant Production Method-10 Colorant production except that 333 parts by weight of wet cyan pigment (CI Pigment Blue 15: 3 with a water content of 70 wt%) was kneaded with a triple roll (Inoue Seisakusho). A cyan colorant j having a pigment content of 50 wt% was prepared in the same manner as in Method-1.

The colorants a to f had good pigment dispersion and excellent workability because the pigment particles were transferred to the resin in a short time and the water was separated and removed completely and in a short time. It was The colorants g to j have problems in quality as a colorant and production efficiency, such as insufficient pigment dispersion and insufficient heat separation for heating and drying. Table 1 shows the results.

Example 1 Second binder resin 95 parts by weight Cyan colorant a 5 parts by weight The second binder resin has a weight average molecular weight Mw of 30,000, a number average molecular weight Mn of 33,000 and Mw. /Mn=10.0, Tg = 5
6 ° C., softening point 110 ° C., acid value 10 mg KOH / g, after mixing the above components with a Henschel mixer, melt kneading with an extruder and crushing with a jet mill,
After classification, the pigment content is 2.5 wt% and the volume average particle diameter is 8μ.
A cyan toner A of m was prepared.

Example 2 The pigment content was 5.0 wt% in the same manner as in Example 1 except that the cyan colorant a was replaced by 10 parts by weight of the magenta colorant b and the second binder resin was changed to 90 parts by weight.
%, And a magenta toner B having a volume average particle diameter of 8 μm was manufactured.

Example 3 The pigment content was 3.0 wt% in the same manner as in Example 1 except that the cyan colorant a was replaced by 6 parts by weight of the yellow colorant c and the second binder resin was changed to 94 parts by weight.
%, A yellow toner C having a volume average particle diameter of 8 μm was produced.

Example 4 The pigment content was 2.5 wt% in the same manner as in Example 1 except that the cyan colorant a was replaced by 5 parts by weight of the cyan colorant d and the second binder resin was changed to 95 parts by weight.
A cyan toner D having a volume average particle diameter of 8 μm was produced.

Example 5 A magenta toner E having a pigment content of 5.0 wt% and a volume average particle diameter of 8 μm was prepared in the same manner as in Example 2 except that the magenta colorant b was replaced with the magenta colorant e.

Example 6 A yellow toner F having a pigment content of 3.0 wt% and a volume average particle size of 8 μm was prepared in the same manner as in Example 3 except that the yellow colorant f was used instead of the yellow colorant c. did.

To 100 parts by weight of each toner of Examples 1 to 6, 0.2 parts by weight of hydrophobic silica and 0.6 parts by weight of hydrophobic titania were externally added and mixed with a ferrite carrier coated with a styrene-acrylic resin. As a developer, the image was evaluated with a commercially available digital full-color copying machine.

Here, the coloring property is evaluated by the ID when the unfixed image transferred on the paper has a fixed toner adhesion amount, and further the pigment content rate (when 100 parts by weight of toner is used). The value obtained by dividing by the ratio (part by weight of pigment) was expressed as a color forming index. Specifically, cyan toner is 0.7 mg
/ Cm ^2, the magenta toner 0.8 mg / cm ^2, yellow toner 0.65 mg / cm ² and then ID Macbeth densitometer when the (RD918: manufactured by Macbeth Co.) was measured,
Cyan toner 0.025 and magenta toner 0.0, respectively
5 and yellow toner 0.03. Color development index = image density ID of each color toner / pigment content rate of each color toner, where ID is a value when the fixed adhesion amount of each color toner is used.

The color reproducibility was evaluated by copying 20,000 sheets using the above-mentioned commercially available digital full-color copying machine using an original document having an image area of 50% and evaluating the image. OHP series
For the evaluation of transparency of the color image produced by the above-mentioned method, the transmission image when projected by an overhead projector was visually judged. When each of the toners of Examples 1 to 6 was imaged, a color image having excellent color development was obtained, and the transparency of the color image of the OHP sheet was also excellent.

Comparative Example 1 A cyan toner G was obtained in the same manner as in Example 1 except that the cyan colorant a was replaced with the cyan colorant g, and an external addition treatment was carried out in the same manner as in Example 1 to form an image. evaluated.

Comparative Example 2 Except that the magenta colorant b was replaced with the magenta colorant h.
Cyan Toner H was obtained in the same manner as in Example 2 and externally added in the same manner as in Example 1 to evaluate the image.

Comparative Example 3 Except that the yellow colorant c was replaced by the yellow colorant i,
Yellow toner I was obtained in the same manner as in Example 3, and Example 1
The image was evaluated by performing external addition processing in the same manner as in.

Comparative Example 4 A cyan toner J was obtained in the same manner as in Example 1 except that the cyan colorant a was replaced with a cyan colorant j, and an external addition process was performed in the same manner as in Example 1 to form an image. evaluated.

The image densities of all the toners of Comparative Examples 1 to 4 were lower than those of the examples, and only images having poor color reproducibility were obtained. The color image of the OHP sheet was dull in color and poor in transparency.

[0071]

By the method for producing a color toner of the present invention, a color toner in which a pigment is finely dispersed in a binder resin can be obtained, and the color resulting from the very small aggregation of pigment particles in the color toner. It has become possible to provide a color toner having excellent reproducibility, color development, and light transmission.

Claims (4)

[Claims] 1. A method for producing a color toner comprising at least a colorant and a binder resin, wherein a first binder resin and a wet pigment having a water content of 40 to 80 wt% are added to a multi-stage blade or multi-stage stirring blade. A color characterized by passing through a first step of kneading with a vertical axis type high-speed kneader equipped to remove water and a second step of kneading the obtained colorant with a second binder resin. Toner manufacturing method. 2. The color toner according to claim 1, wherein the kneading temperature in the first step is equal to or higher than the glass transition temperature of the first binder resin and substantially lower than 100 ° C. Production method. 3. The first binder resin is a linear polyester resin, and the polyester resin comprises ethylene glycol in the dihydric alcohol component constituting the polyester resin in an amount of 20 wt% or more of all alcohol components. A linear polyester resin containing a glass transition temperature Tg
= 65 ° C. or less, weight average molecular weight Mw = 5,000 to 20,000,
The method for producing a color toner according to claim 1, wherein Mw / Mn = 3.0 or less and an acid value of 15 mgKOH / g or less. 4. The second binder resin is a non-linear polyester resin, and the weight average molecular weight Mw = 20,000 to 60,000, Mw / M.
4. The method for producing a color toner according to claim 1, wherein n = 6.0 or more and an acid value of 15 mgKOH / g or less.