JPH07160042A - Toner for electrostatic charging image development and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide toner having always stable electrification performance regardless of seasonal variation (manufacturing environment) by mixing together coloring particles consisting of binding resin and a coloring agent, and inorganic fine particles, while radiating microwave. CONSTITUTION:Coloring particles consisting of at least binding resin and a coloring agent are mixed with inorganic fine particles, while radiating microwave. For the binding resin, there is polystyrene series resin, styrene-acryl series copolymerization resin, styrene-butadiene copolymerization resin, polyester series resin, epoxy series series resin, or the like. The coloring agent is 2-20 pats against the binding resin of 100 weight parts, favorably 3-15 parts are desired to be added. For the inorganic fine particle, there is silica, titania, alumina, barium titanate, zirconia, silicon carbide, silicon nitride, or the like. For the microwave, electromagnetic wave of frequency 915MHz, 2450MHz capably of being utilized as industrial heating are used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic charge image and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, an electrostatic image developing toner is manufactured, for example, as follows. That is, it is roughly classified into a dry type (kneading / pulverization method) and a wet type (polymerization method). Among these methods, the currently predominant manufacturing method is a dry manufacturing method.

According to this method, a binder resin, a colorant, a toner raw material such as a charge control agent and a fixability improver are premixed and dispersed, and then heated and kneaded to add these various additives to the binder resin. After kneading so as to be uniform and cooling, pulverization and classification are performed to adjust to a desired particle size distribution. Then, a surface treatment agent (usually called an external additive) is added and mixed to obtain a final product.

It is easily inferred that the performance of the toner particles produced by this method is greatly influenced by the final step (external additive mixing step).

That is, the purpose of mixing the external additive is to improve the fluidity of the toner as a first purpose, and at the same time to control the chargeability of the toner as a second purpose.

However, various substances such as a binder resin, a colorant, a fixing property improving agent, and a charge control agent are unevenly distributed on the surface of the colored particles in a microscopic manner.
When the inorganic fine particles are added and mixed, they tend to selectively adhere to places where they are easily electrostatically adhered. At this time, a major problem is the influence of water.

That is, since the selectivity of the external additive to be adhered depends on the electrostatic factor, if the amount of water in the system at the time of mixing the external additive, particularly the amount of adsorbed water on the surface of the colored particles is different, the external additive is added. The state of adhesion of the agent is different, resulting in a difference in chargeability of the finished toner.

In other words, depending on the environment during toner production (particularly when external additives are mixed), there will be a difference in the performance of the resulting toner.

As conventional techniques for solving this problem, there are, for example, Japanese Patent Laid-Open Nos. 3-116053 and 5-66606. That is, Japanese Patent Laid-Open No. 3-116053 describes that the saturated water content of the external additive (fluidizing agent) to be added is regulated within a certain range and the external additive is added, but only the external additive is added. With the saturated water content regulation of, the effect is insufficient. Further, Japanese Patent Laid-Open No. 5-66606 discloses a method in which an external additive to be added is humidified in advance and the humidified external additive is added and mixed. Even in this method, only the external additive to be added is specified, and the amount of water adsorbed on the surface of the colored particles as the toner base is not constant, so that an insufficient effect is currently obtained.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a toner for developing an electrostatic charge image which always has stable charging performance regardless of seasonal fluctuation (manufacturing environment). .

[0011]

The present invention is proposed in order to achieve the above-mentioned object, and specifically, in the above-mentioned external additive mixing step, the influence of moisture should not occur. It was found that it is important to complete the present invention.

That is, the object of the present invention is achieved by the following (1) and (2).

(1) In the method for producing a toner for developing an electrostatic image, at least in the step of mixing colored particles composed of a binder resin and a colorant and inorganic particles, microwave irradiation is performed during the mixing. A method for producing a toner for developing an electrostatic charge image, which comprises:

(2) In the toner for developing an electrostatic charge image, the electrostatic charge image developing is characterized by undergoing a step of mixing colored particles composed of at least a binder resin and a colorant and inorganic fine particles while irradiating with microwaves. For toner.

As the mixing device used for mixing the external additives, any device can be applied as long as it is a commercially available mixing device equipped with a microwave irradiation mechanism.

[0016] Note that the general microwave, a wave of very short wavelength, wavelength 3～30Cm (frequency 1000MH _Z
～10000MH _Z) about but collectively the radio wave, the microwave is used in the present invention, the electromagnetic wave of the electromagnetic wave (especially 2450MH _Z frequency 915MH _Z · 2450MH _Z that may be currently available as an industrial heating (high frequency induction heating) ).

Further, as a matter of course, the microwave output is adjusted and used so that the colored particles do not cause the fusion phenomenon.

[0018]

The present inventors have studied to provide an electrostatic image developer having stable charging performance regardless of environmental and seasonal fluctuations, that is, a method for removing water contained in the system. As a result of diligent study, it was found that a toner having the most stable charging performance can be obtained by removing water in the system by irradiating with microwaves while mixing the colored particles and the inorganic fine particles when mixing the external additive. .

That is, when water is removed by a general heating method, heating is excessive under the conditions for vaporizing the water in the system, and the surface of the colored particles becomes in a molten state, so that the inside of the external additive mixing apparatus is heated. Therefore, it was found that appropriate conditions cannot be found because a blocking phenomenon occurs between colored particles.

On the other hand, in the heating method using microwaves, the heating condition for the same microwave output varies depending on the characteristics of the material to be heated (particularly depending on the dielectric loss coefficient). In other words, a substance with a large dielectric loss coefficient will be in a state similar to general surface heating (shallow surface heating), and it will not be possible to heat the inside. On the contrary, a substance with a small dielectric loss coefficient will absorb almost all microwaves. It is known that it is difficult to heat without heating. Most of the colored particles are a binder resin, and the binder resin has a very small dielectric loss coefficient as described above, and therefore does not generate much heat when irradiated with microwaves. On the other hand, the problematic moisture is selectively heated and easily vaporized because of its large dielectric loss coefficient.

As the binder resin for the colored particles that can be used in the present invention, it is possible to use known ones, specifically, polystyrene resin, styrene-acrylic copolymer resin, styrene. -Butadiene-based copolymer resin, polyester-based resin, epoxy-based resin, etc. may be mentioned, and if necessary, two or more of them may be mixed and used. Further, a part of these binder resins may be crosslinked.

On the other hand, as the colorant used in the present invention, it is possible to use already known ones. If necessary, the colorant may be surface-treated to improve its dispersibility. May be. In addition, as the colorant when used as a color toner, any colorant can be used as long as it imparts the color required for the developer to the developer. As these colorants, inorganic and organic pigments are preferably used, and organic pigments are particularly preferably used.
Further, for these pigments, it is more preferable to use a masterbatch-treated colorant in order to ensure dispersibility.

Concretely, as the black ones, commercially available carbon black (hereinafter referred to as CB) and C.I. grafted with a polymerizable monomer or the like are used. B. C. which has been surface-treated with a surface-treating agent such as a silane coupling agent and an aluminum coupling agent.
B. Etc. are used.

As the pigment for magenta or red,
C. I. Pigment Red 2 C.I. I. Pigment Red 3 C.I. I. Pigment Red 5 C.I. I. Pigment Red 6 / C. I. Pigment Red 7 C.I. I. Pigment Red 15 C.I. I. Pigment Red 16 / C.I.
I. Pigment Red 48: 1 C.I. I. Pigment Red 53: 1 C.I. I. Pigment Red 57: 1 C.I. I.
Pigment Red 122 / C.I. I. Pigment Red 123 ・
C. I. Pigment Red 139 / C.I. I. Pigment Red 144, Pigment Red 149, C.I. I. Pigment Red 166 / C.I. I. Pigment Red 177 / C.I. I. Pigment Red 178 / C.I. I. Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31 / C. I. Pigment Orange 43 / C.I. I. Pigment Yellow 12 / C.I.
I. Pigment Yellow 13 / C. I. Pigment Yellow 14 / C.I. I. Pigment Yellow 15 / C.I. I. Pigment Yellow 17 / C.I. I. Pigment Yellow 93 / C.I.
I. Pigment Yellow 94 / C.I. I. Pigment Yellow 138. Examples of pigments for green or cyan include C.I. I. Pigment Blue 15 / C.I. I. Pigment Blue 15: 2 C.I. I. Pigment Blue 15: 3
-C. I. Pigment Blue 16 / C.I. I. Pigment Blue 60 / C.I. I. Pigment Green 7 and the like.

These colorants may be used alone or in combination of two or more, depending on the desired color tone, and regarding the addition amount, 100 parts by weight of the binder resin (in this specification, particularly Unless otherwise stated, "parts" means "parts by weight.") 2 to 20 parts, particularly preferably 3 to
It is desirable to add 15 parts.

As the fixing performance improver, known ones can be used and are not particularly limited. For example, the number average molecular weight (the number average molecular weight is high temperature GPC Shows the molecular weight conversion value of polystyrene) 1500-5000 low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight polyethylene-
Polyolefin wax such as low molecular weight polypropylene copolymer, microwax, high melting point paraffin wax such as Fischer-Troche wax, and ester wax such as fatty acid lower alcohol ester, fatty acid higher alcohol ester, fatty acid polyhydric alcohol ester, amide A wax or the like can be preferably used.

As the charge control agent, known charge control agents can be used and are not particularly limited. For example, a nigrosine dye, a quaternary ammonium salt compound, an alkylpyridinium compound, and a divalent divalent compound. It is possible to use organic salts or complexes containing the above metals.

The inorganic fine particles externally added to the colored particles include silica, titania, alumina, barium titanate,
Examples thereof include magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide and silicon nitride. These may be subjected to a hydrophobizing treatment and used, and particularly hydrophobized silica is preferably used. Further, in recent years, as a photoreceptor, a negatively chargeable organic photoreceptor has become mainstream, and a toner having a positive chargeability has been demanded. In such a case, an amino-modified silane coupling agent is required. Hydrophobic silica surface-treated with an amine-modified silicone compound such as amino-modified silicone oil, polysiloxane ammonium salt, organopolysiloxane and 3-aminopropyltriethoxysilane can be preferably used.

Further, as other external additives, a lubricant such as zinc stearate or polyvinylidene fluoride, or a fixability improving agent such as low molecular weight polypropylene may be added and mixed at the same time with the inorganic fine particles.

The amount of these external additives added depends on the total toner.
The range of 0.01 to 10 parts is preferable, and more preferably 0.05 to 8
A range of parts is preferred.

As a device used for mixing the external additive, a commercially available mixing device such as a fluidized bed type mixer, a high speed stirring type mixer, or a stirring mixer is equipped with a microwave oscillating section. If so, any device can be applied. In addition, in order to use the microwave energy with high efficiency, an accessory device such as an isolator, a power monitor, an EH tuner may be connected between the oscillator and the heating unit.

[0033]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Method for producing colored particles Toner composition Binder resin Styrene-acrylic copolymer resin Coarse pulverized product 100 parts by weight Coloring agent Granular carbon black 10 parts by weight Release agent Low molecular weight polypropylene 3 parts by weight Release agent Bisstearin Acid amide 5 parts by weight The above toner composition was charged into a Nauter type mixing device and premixed, and then the mixture was continuously melted and kneaded by a twin-screw kneading extruder and then cooled by a cooling roller. A coarsely pulverized product was obtained, and then finely pulverized and classified to obtain colored particles having a volume average particle diameter of 8.5 μm.

Example (1) 100 parts by weight of the colored particles and 1.0 part by weight of hydrophobic silica were charged into a high-speed stirring type mixing device (Hexel mixer) equipped with a microwave oscillating mechanism, and the mixture was irradiated with microwaves to the outside. Toner 1 was obtained by mixing the additives. The environment when the external additives were mixed was a temperature of 33 ° C. and a relative humidity of 85%.

Example (2) Toner 2 was prepared in the same manner as in Example (1) except that the environment when the external additive was mixed was a temperature of 23 ° C. and a relative humidity of 63%.
Got

Example (3) Toner 3 was prepared in the same manner as in Example (1) except that the environment when the external additive was mixed was a temperature of 8 ° C. and a relative humidity of 22%.
Got

Comparative Example (1) Toner 4 was obtained in the same manner as in Example (1) except that the microwave irradiation was not carried out when the external additive was mixed.

Comparative Example (2) Toner 5 was obtained in exactly the same manner as in Example (2) except that microwave irradiation was not carried out when the external additive was mixed.

Comparative Example (3) Toner 6 was obtained in exactly the same manner as in Example (3), except that microwave irradiation was not carried out at the time of mixing the external additive.

Comparative Example (4) In Example (1), stirring and mixing were carried out while heating from the jacket mounted on the wall surface of the mixing apparatus without irradiation of microwaves when mixing the external additive. However, the toner 7 was tried to be obtained, but the fusion phenomenon occurred in the mixing device, and the toner having a desired particle diameter could not be obtained. The inlet temperature of the hot water circulated in the jacket at this time was 60 ° C.

Comparative Example (5) Except for the fact that the external additive used in Comparative Example (1) was one that had been preliminarily irradiated with microwaves to remove water before being charged in a high-speed stirring type mixer, it was completely excluded. Toner 8 was obtained in the same manner.

The charging properties of the various toners produced as described above were evaluated by the method described below.

<Evaluation of Toner Charging Property> Preparation Method of Developer Various toners prepared in Examples and Comparative Examples and the carriers shown below were used in a toner concentration of 5.0% by weight (total weight: 20.0%).
g) Prepared into a glass sample tube with an inner diameter of 25 mm and a height of 40 mm, and adjusted the humidity for 3 hours in an environment of 20 ° C and relative humidity of 60%, and then shaker (manufactured by Yayoi Co .; Model New YS-8D).
2 at a shaking angle of 45 ° and a shaking strength of 200 strokes / minute
The developer was adjusted by shaking and mixing for 0 minutes.

Carrier used Core particles Spherical ferrite particles having an average particle size of 80 μm Coating resin Fluorine-based resin Resin coverage 2.6% by weight (1) Method of measuring average charge amount of developer The average charge amount was measured.

(2) Evaluation Method of Uniformity of Charging of Toner Particles The prepared developing agent is measured for its charging amount distribution by a charging amount distribution measuring device (manufactured by Hosokawa Micron Co., Ltd .; model Espert Analyzer).

Evaluation was carried out by the size of the half-value width of the maximum peak of this charge amount distribution (the cut width when the distribution was cut at a value of half the maximum peak height in the distribution). (If the distribution is sharp, the half-width is small, and conversely if it is broad,
Half-width becomes large. ) Table 1 shows the evaluation results of these charging properties.

[0048]

[Table 1]

With respect to the three types of toner 1, toner 4 and toner 8, the following chargeability under high temperature and high humidity was also evaluated.

The method for adjusting the developer under a high temperature and high humidity environment will be described below.

Method of adjusting developer under high temperature and high humidity environment Toner 1, toner 4 and toner 8 and the carrier shown below and an inner diameter of 25 mm so that the toner concentration becomes 5.0% by weight (total weight 20.0 g), A glass sample tube with a height of 40 mm was placed in the sample tube, and the humidity was adjusted to 33 ° C; 80% relative humidity for 3 hours, and then shaken with a shaker (Yayoi Co .; Model New YS-8D) at a shaking angle of 45 °. The developer was adjusted by shaking and mixing at 200 strokes / minute for 20 minutes.

Carriers Used Core Particles Spherical Ferrite Particles with Average Particle Diameter 80 μm Coating Resin Fluorine Resin Resin Coverage 2.6% by Weight Table 2 shows the evaluation results of the charging property in a high temperature and high humidity environment.

[0053]

[Table 2]

The reason why the charging characteristics (uniformity of charging property) of the developer under the environment of high temperature and high humidity is almost the same as under the environment of normal temperature and normal humidity is that the external additive once attached to the surface of the colored particles ( In this case, the hydrophobic silica) is very small, and since the external additive itself has a very high chargeability, it has a strong electrostatic adhesive force, and therefore remains in the state in which it was once treated. Therefore, it is considered that although the overall charge level changes depending on the environment, the sharpness of the charge amount distribution is determined by the condition at the time of the external addition process.

Therefore, it is clear that the microwave irradiation during the external additive treatment of the present invention has a great effect on the improvement of the charging uniformity and the addition of the charging stability throughout the four seasons. .

[0056]

According to the present invention, it is possible to provide a toner for developing an electrostatic charge image, which always has stable charging performance irrespective of seasonal variation (manufacturing environment).

Claims (2)

[Claims] 1. A method for producing a toner for developing an electrostatic charge image, wherein at least in a step of mixing colored particles composed of a binder resin and a colorant and inorganic fine particles, a microwave is irradiated during the mixing. A method for producing a toner for developing an electrostatic image, which is characterized. 2. A toner for developing an electrostatic charge image, which comprises a step of mixing colored particles consisting of at least a binder resin and a colorant and inorganic fine particles while irradiating microwaves. toner.