JPH04269765A - Production of electrophotography developer - Google Patents

Abstract

PURPOSE:To lower melting and kneading temps. and to allow the uniform and fine dispersion of internal additives, such as coloring agents, charge control agents and wax by adding and mixing liquid to and with developer raw materials prior to melting and kneading. CONSTITUTION:The liquid from a pump 9 is injected by a spray nozzle 8 to the raw materials charged into a raw material mixer 1, by which the raw materials are mixed. The mixed toner raw materials are sent from a piping 2 to a raw material supplying machine 3 and are further sent from a piping 4 to a kneading machine 5, by which the raw materials are kneaded. Since the liquid is added and mixed to and with the developer raw materials prior to the melting and kneading in such a manner, the uniform raw materials for melting and kneading are obtd. and further, the resin temp. at the time of the melting and kneading is nearly evenly lowered by the latent heat of evaporation of the uniformly dispersed liquid.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for producing an electrophotographic developer, and in particular to a method for producing a colorant, a charge control agent, and a charge control agent in a toner.
This invention relates to a method for improving the dispersion of internal additives such as wax.

0002

[Prior Art] A toner manufacturing method involves mixing a colorant, a binder resin, and if necessary, a charge control agent and an anti-offset agent, melting the resulting mixture, kneading it, and then finely pulverizing it.・The pulverization method is the usual method, and depending on the requirements for toner characteristics (resolution, fog, etc.), a classification process is provided to obtain toner particles in a specific particle size range.
If necessary, a mixing step is provided for adhering and fixing a fluidity imparting agent, a charge control agent, a cleaning aid, etc. to the surface of the toner particles.

In electrophotographic developers, it is essential to improve the dispersibility of colorants, charge control agents, and anti-offset agents in the toner, but the dispersibility of these agents depends on the quality of kneading during melt-kneading. A lot depends on. The viscosity of the binder resin is a major factor that determines the kneading properties, and the viscosity determines whether or not it can effectively receive the shearing force applied by the kneader. As a method to lower the resin viscosity to a state where good kneading properties can be obtained,
As shown in Japanese Unexamined Patent Publication No. 61-50624, there is a method of injecting a liquid component into a kneading processing device. According to this method, the resin temperature ranges from about 10°F to about 60°F (about 5.6°F).
°C to about 33.3 °C), resulting in a more desirable state of dispersion.

FIG. 2 shows an example of the toner manufacturing process in this case, in which the toner raw materials mixed in the raw material mixer 1 are sent from a pipe 2 to a raw material supply machine 3, and further from a pipe 4 to a kneader 5. Sent. In the kneading machine 5, the liquid from the pump 9 is injected through the spray nozzle 8, and kneading is performed. Next, it is discharged onto a cooling conveyor 6 and coarsely crushed by a crusher 7.

[0005]

However, the above conventional method has the following drawbacks. Depending on the type of binder resin to be kneaded, changes in lots, and changes in kneading conditions (changes in the supply amount of kneading raw materials, the rotation speed of the screw or rotor of the kneader, etc.), the time at which the resin melts in the kneader (point ) changes, so if the liquid injection position is fixed, injection will not be performed at the appropriate position as a result, resulting in defective injection. Conversely, there are problems in that it is difficult to select an appropriate injection position depending on the raw materials to be kneaded and the kneading conditions, and it is also difficult to change the injection position each time. However, when kneading highly abrasive raw materials such as magnetic powder, the nozzles that are the injection means will be worn down by the kneaded material, impairing the nozzle's function and causing poor liquid injection. There's a problem. Therefore, depending on the conventional method described above, it is difficult to always obtain the desired uniform dispersion.

[0006] The present invention has been accomplished with the object of improving the drawbacks of the conventional techniques as described above. That is, an object of the present invention is to provide a method for producing an electrophotographic developer that can lower the melt-kneading temperature and uniformly and finely disperse internal additives such as colorants, charge control agents, and waxes. There is a particular thing.

[0007]

[Means for Solving the Problems] The present inventors have discovered that the above object can be achieved by adding a liquid to the raw material of an electrophotographic developer before melt-kneading, and have completed the present invention. reached. That is, the present invention provides a method for producing an electrophotographic developer (hereinafter referred to as developer) in which raw materials for an electrophotographic developer are melt-kneaded, then pulverized, and classified.
It is characterized by adding and mixing a liquid to the developer raw material before melt-kneading.

FIG. 1 shows an example of the toner manufacturing process according to the present invention. In this example, a spray nozzle is provided in the raw material mixer, and a liquid is injected from the spray nozzle during mixing to uniformly mix the raw material before kneading and the liquid, and then melt-kneading is performed. In the figure, liquid from a pump 9 is injected into the raw material fed into the raw material mixer 1 through a spray nozzle 8, and mixing is performed. The mixed toner raw materials are sent from piping 2 to raw material supply machine 3, and further sent from piping 4 to kneading machine 5, where kneading is performed. Next, it is discharged onto a cooling conveyor 6 and coarsely crushed by a crusher 7.

Electrophotographic developers to which the present invention can be applied include toners in one-component developers and two-component developers, and magnetically dispersed carriers used in two-component developers.

[0010] Raw materials used in producing toner include the following. As a binder resin,
Polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic resin, polyester resin, Examples include vinyl chloride resin and epoxy resin. Colorants include carbon black, aniline black, nigrosine dye, aniline blue, chrome yellow, ultramarine blue, oil red,
Examples include phthalocyanine blue, lamp black, rose bengal, and mixtures thereof.

In the case of magnetic toner, the colorant is:
Known magnetic materials such as iron, magnetite, ferrite, etc. can be used. As the charge control agent, nigrosine dye, chromium-containing complex, quaternary ammonium salt, etc. are used, and these may be used appropriately depending on the polarity of the toner particles. As the offset inhibitor, polyolefins (eg, polyethylene, polypropylene), alkylamides (eg, ethylene bisstearylamide), polytetrafluoroethylene, etc. are used.

[0012] As the raw materials used in producing the magnetic material dispersed carrier, the same raw materials used in producing the above-mentioned toner can be used.

The liquid to be added has a boiling point lower than the melting temperature of the resin. in particular,
Those having a boiling point of about 50° C. to about 150° C. and a latent heat of vaporization of 0.80 kJ/g or more per unit amount of liquid can be preferably used. Examples of these include water (latent heat of vaporization: 2.2
6kJ/g, boiling point: 100℃), methanol (latent heat of vaporization: 1.10kJ/g, boiling point: 64.7℃), ethanol (latent heat of vaporization: 0.84kJ/g, boiling point: 78.5℃)
Examples include aliphatic alcohols such as These may also be used in the form of mixtures. Among them, water
Since the latent heat of vaporization is large, the cooling effect is high, and since a solvent vapor recovery system is not required, it has the advantage of being easy to handle. Note that if the latent heat of vaporization of the liquid to be added is low, a large amount of liquid will be required, and the manufacturing efficiency of the developer will decrease, resulting in an increase in cost. Furthermore, there may be cases where the resin temperature cannot be sufficiently lowered during melt-kneading. Therefore, it is desirable that the latent heat of vaporization of the liquid is within the above range.

The liquid is added in an amount of 1 to 30 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of toner raw materials before kneading. When the liquid is water, by adding 1% to the weight of the toner raw material before kneading, it becomes possible to lower the resin temperature by about 6°C to 30°C. Note that if the amount of liquid added is too large, the liquid may be distributed ubiquitously during mixing of the raw materials, making it impossible to sufficiently lower the resin temperature during melt-kneading, so the above range is appropriate.

[0015] Examples of the apparatus used in the present invention include the following. Examples of the raw material mixer include container rotating type and container fixed type mixers. Specific examples include a W cone, a V blender, a Henschel mixer, a UM mixer, a rocking mixer, and the like. In the present invention, these raw material mixers are provided with a liquid injection (addition) device. As the liquid injection (addition) device, commercially available spray nozzles can be used without any particular problem, but the device is not limited thereto. In addition, it is particularly preferable to use a material that has corrosion resistance and rust prevention properties.

[0016] As the kneading machine, one having one or more rotating shafts (screws, rotors, rolls, etc.) is used. Specifically, extruders, Banbury mixers, continuous kneaders, roll mills, etc. may be used.

In the present invention, since a liquid is added to the developer raw material before melt-kneading and mixed, a uniform raw material for melt-kneading can be obtained, and furthermore, the latent heat of vaporization of the uniformly dispersed liquid causes melt-kneading. The resin temperature can be lowered almost uniformly. Therefore, the kneaded product can have a constant melt viscosity, and internal additives such as colorants, charge control agents, and wax can be finely and uniformly dispersed. In addition, since the resin temperature during melt-kneading can be lowered,
Another advantage is that charge control agents and colorants with low decomposition points can be used. In particular, when the resin temperature during melt-kneading is high, resin with a low melting temperature tends to come out to the surface, reducing the fluidity of the developer, but the present invention does not have such drawbacks and the developer It has the effect of having good fluidity.

[0018]

[Examples] The present invention will be specifically explained below with reference to Examples. Example 1 The following materials were used as toner raw materials. Styrene-n-butyl acrylate (
80:20) copolymer
85.5 parts by weight Carbon black Regal 330 (manufactured by Cabot)
6 parts by weight Viscoel 660P (manufactured by Sanyo Chemical Industries, Ltd.)
6 parts by weight Bontron P-51 (manufactured by Orient Chemical Industry Co., Ltd.) 1.5 parts by weight
PE-130 (Hoechst A.G.)
1 part by weight 20 kg of these toner raw materials were placed in a 75 liter Henschel mixer (manufactured by Mitsui Miike Kokoki Co., Ltd.), and
Mixed for 100 seconds at rpm. 20 seconds after the start of mixing, 200 g of water (1% based on the toner raw material) is sprayed from a spray nozzle (full cone nozzle 1/4 MJ 100S303W, manufactured by Ikeuchi Co., Ltd.) attached to the Henschel mixer.
was injected at a pressure of 2 kg/cm2. The obtained toner raw material was passed through a quantitative feeder and kneaded with a twin-screw continuous kneader. The kneading conditions were a feed rate of 40 kg/hr and a kneader rotor rotation speed of 1000 rpm. The temperature at the time of discharge of the kneaded material was 144.2°C.

Example 2 Kneading was carried out using the same water-added toner raw material as in Example 1, except that the supply rate was 70 kg/hr. The discharge temperature of the kneaded material was 148.2°C.

Example 3 Kneading was carried out using the same water-added toner raw material as in Example 1, except that the supply rate was 100 kg/hr. The discharge temperature of the kneaded material was 150.2°C.

Comparative Example 1 Water was not added during mixing of the raw materials, but 1% of water was injected into the kneader based on the amount of raw materials supplied through the injection nozzle installed in the kneader, and the kneading conditions were set to 70 kg. /hr, and the rotation speed of the kneader was 1000 rpm. However, in this case, water was blown out from the degassing port provided in the kneading machine, making it impossible to pour water into the toner raw material during kneading. The discharge temperature of the obtained kneaded material was 161.3°C.

Comparative Example 2 1% water was injected into the kneaded product in the same manner as in Comparative Example 1, except that the kneading conditions were changed to 100 kg/hr. However, in this case as well, as in Comparative Example 1, water could not be poured into the toner raw material during kneading, and the temperature at which the kneaded product was discharged was 174.4°C.

Microscope (TEM) photographs were taken of the kneaded materials obtained in Examples 1 to 3 and Comparative Examples 1 and 2, and the dispersion units of the charge control agent and anti-offset agent were measured. The results are shown in Table 1. In addition, the kneaded materials obtained in the Examples and Comparative Examples were subjected to a hammer mill, jet mill pulverization, and fine powder classification, and the volume average particle diameter was measured using a Coulter Counter TA-II model (manufactured by Coulter Electronics). 10.5±0.5μm, 5μ or less Fine powder amount: 15
A toner of less than % by number was obtained. For these toners,
Cohesion degree and compression ratio were measured. The results are shown in the column of classified products in Table 2.

[0024]The degree of agglomeration was determined at 45°C and 50% RH.
After leaving it for 17 hours in an environment of 1000 μm and 1
The amount of toner on each sieve is divided by the amount of toner that has passed through a 0.6 μm mesh sieve, and the percentage is shown. Moreover, the compression ratio shows the value measured with a powder tester (manufactured by Hosokawa Micron Co., Ltd.).

As is clear from Tables 1 and 2, the kneaded products and toners of Examples have finely dispersed colorants, charge control agents, and anti-offset agents, and also have excellent powder fluidity. In contrast, it can be seen that the kneaded product and toner of the comparative example in which water could not be injected had a poor dispersion state and poor powder fluidity.

Furthermore, 20.4 parts by weight of fine titanium oxide powder with an average particle size of 0.4 to 0.5 μm was added as an external additive to 1000 parts by weight of the toner after the fine powder classification, and the mixture was mixed in a 5 liter Henschel mixer for 10 parts by weight. Mixed for a minute. The degree of cohesion and compression ratio of these toners were also measured. The results are shown in the column of external additive mixture in Table 2.

Furthermore, 10 parts by weight of these toners and 90 parts by weight of carrier were mixed to prepare an electrophotographic developer, and copy running was performed on 10,000 copies using a copying machine (FX5075, manufactured by Fuji Xerox Co., Ltd.). As a result, the toner developers of Examples 1 to 3 produced good images with no particular problems, but the developers of Comparative Examples 1 and 2 had poor dispersion and poor powder fluidity. In the case of using bad toner, a lot of fogging was observed, and furthermore, the toner caused blocking inside the developing machine. Additionally, toner adhesion to the carrier occurred.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Effects of the Invention] In the present invention, since a liquid is added to the developer raw material before melt-kneading, a uniform raw material for melt-kneading can be obtained, and therefore, the resin temperature during melt-kneading can be lowered almost uniformly. A developer can be obtained in which internal additives such as a colorant, a charge control agent, and a wax are uniformly dispersed. Further, the obtained toner exhibits the effects of less agglomeration and good powder fluidity.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the manufacturing process of the present invention.

FIG. 2 is a flowchart showing a conventional developer manufacturing process.

[Explanation of symbols]

1 Raw material mixer 2 Piping 3 Raw material feeder 4 Piping 5 Kneading machine 6 Cooling conveyor 7 Crushing machine 8 Spray nozzle 9 Pump

Claims (1)

[Claims] 1. A method for producing an electrophotographic developer in which raw materials for an electrophotographic developer are melt-kneaded and then pulverized and classified, characterized in that a liquid is added to and mixed with the raw materials before melt-kneading. A method for producing a photographic developer.