JPH02173666A - Manufacture of spherical particles for toner - Google Patents

Abstract

PURPOSE:To facilitate recovery of a solvent and to reduce cost by reducing pressure of an aqueous system stably dispersing oil drops containing toner components. CONSTITUTION:The spherical toner particles are obtained by melt mixing a binder resin, carbon black, a dye, and a wax, cooling the kneaded mixture, dissolving and dispersing it into a solvent mixture, then, dropping this liquid product into water 2 containing a small amount of gelatin, stirred at high speed with a homogenizer 4 rotating at high speed, dispersing it in oil drops 3 into the water 2, then, heating the water 2 with a heater 6 set under a water vessel 1, evaporating the solvents with stirring, filtering the solid, and washing with water and drying it, thus permitting evaporation and removal of the solvents to be rapidly carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for producing toner for electrostatic image phenomenon used in electrophotography, electrostatic recording, etc.

(b) Conventional technology In recent years, an electrostatic charge image of an image to be transferred is formed using an electrophotographic method or an electrostatic recording method, and this is made visible with a developing toner and transferred to a transfer paper, etc. 1', after P Lk. , a method of fixing the image to produce a visible image is widely used.

The toners mentioned above that are subjected to the electrostatic 6:j image phenomenon include two-component toners that are mixed with a carrier such as iron powder or glass beads, and one-component toners that do not require a carrier. All of these toners are usually made by adding a thermoplastic resin as a binder, a young agent such as carbon black, a dye, or a pigment, and a charge control agent, and in the case of a magnetic toner, further adding a magnetic substance, etc. It is manufactured by melting, kneading, pulverizing and classifying.

The toner produced through the pulverization process as described above has an amorphous shape and therefore has poor fluidity, resulting in undesirable results in terms of storage stability. For this reason, a method has been adopted in which a fine powder such as silica is added to the toner surface as an external additive. However, since the step of adding the external additive described above is a separate step, it results in an increase in cost, and the resulting toner does not have sufficient fluidity. Therefore, recently, solution-based production methods such as submerged drying method and suspended 1:1 polymerization method, which do not require the above-mentioned pulverization step and external additive addition step, have been developed.
Research is being conducted on methods for producing spherical toner, and attempts are being made to improve storage stability and other properties, and to reduce costs.

Furthermore, as a fixing method, toner melting and fixing using a heat roller is common, but fixing using a heating method requires a heat source, which consumes a large amount of power.
- It has drawbacks such as the need for warm-up. To address these shortcomings, energy saving has been achieved by using toner with a low fusing temperature and by adopting a pressure fusing method.
A lot of research is being carried out on zero warm-up time. All of these toners use low-molecular agitation polymers and waxes, and undergo plastic deformation at low temperatures or pressure. If such a toner is produced by a pulverization method, the binder tends to be fused due to heat during pulverization, making stable production very difficult. For this reason, solution methods such as the submerged drying method and the turbidity method have been mainly investigated for the production of these toners.

(c) Problems to be Solved by the Invention However, in the 1,1-liquid distribution drying method, the solvent is usually evaporated and removed by ripening and stirring, which takes a long time to produce, consumes a large amount of energy, and reduces efficiency. This is not a good drying method. In addition, recovering the volatilized solvent is necessary to prevent pollution and reduce costs, and conventional drying methods have their limits.

This invention has been made in view of the above circumstances, and provides a toner that efficiently removes solvent and facilitates recovery of the solvent in the submerged drying method, which is a highly versatile method for producing spherical toner. The present invention aims to provide a method for producing spherical particles for use in the production of spherical particles.

(d) Means for Solving the Problems Thus, according to the present invention, a solution of a hydrophobic solvent containing toner components is prepared, the solution is dispersed in the form of oil droplets in an aqueous medium, and the system is reduced in pressure. A method for producing spherical particles for toner is characterized in that spherical toner particles are obtained by volatilizing and removing a hydrophobic solvent, and a solution of a hydrophobic solvent containing toner components is prepared, and the solution is dissolved in an aqueous medium. Provided is a method for producing spherical particles for toner, characterized in that U. .

That is, the method of this invention accelerates the volatilization of the solvent by reducing pressure or introducing an insoluble gas in the submerged drying method,
It is possible to achieve the above purpose. It is also possible to further shorten the production time by using conventional heat and stirring in combination.

The rate of volatilization of volatile solvents becomes even greater under reduced pressure or gas flow, and these closed systems ensure a flow path for the volatile solvent, so a low-temperature trap should be provided at one point in the flow path. This makes it possible to efficiently collect the volatile solvent.

The toner component used in the method of the present invention means a toner component having a composition used in the field concerned, and specifically includes a thermoplastic resin of 80 to 9 OiR nail% as a binder,
Colorants such as dyes and pigments 5-15%, charge control agent 1-5%
It is composed of weight %, etc. Examples of the thermoplastic resin include borisdyrenes, styrene copolymers such as styrene-methacrylic acid ester and acrylic ester copolymer, polyvinyl chloride, polyvinyl acetate, polymethacrylic ester, epoxy resin, polyester resin, and polyamide. Resin, polyethylene, polyurethane, ethylene-
Resins such as vinyl acetate copolymers, petroleum resins, and paraffin waxes may be used alone or in combination. Examples of the coloring agent include carbon black and the like. Examples of the charge control agent include nigrosine-based dyes for positive polarity toners and organometallic complexes for negative polarity toners. In addition, the toner components may further contain common fluidizing agents, magnetic materials, and the like.

Examples of the fluidizing agent include colloidal silica, while examples of the magnetic material include metals containing ferromagnetic elements such as iron, cobalt, and nickel, including ferrite and magnetite, and compounds such as alloys. can be mentioned.

Preparation of the toner components is preferably carried out according to the usual formulations in the field, and it is particularly preferred that the colorant is used in an amount of 5 to 1% of the toner components. The particle size of this colorant is preferably from several 10 to several 100.

In this invention, the toner component prepared as described above is dissolved or dispersed in a hydrophobic solvent that is substantially incompatible with water and can be volatilized relatively easily, and then By a conventionally known method, the so-called in-liquid drying method, in which oil droplets of a predetermined size are dispersed and maintained in an aqueous system containing a dispersion stabilizer, and then the hydrophobic solvent is volatilized.
Manufactured into spherical toner particles. Suitable examples of the hydrophobic solvent include organic solvents such as toluene, chloro[1-form, and diethyl ether, but are not limited to these, and these can be used alone or in any combination. In the above dispersion, each oil droplet is usually several μ
It is adjusted to a size of m-several lOμm.

For this adjustment, it is preferable to use, for example, a homogenizer, and the rpm is 5,000 to 110,000 rpm, and more preferably 7,000 to 8,000 rp111. The above-mentioned size adjustment and uniform dispersion are achieved by the high-speed rotation of the .

After this homogenization is achieved, it is subjected to drying conditions.

The drying is achieved by reducing the pressure or introducing a gas into the uniformly dispersed suspension at a predetermined temperature for a predetermined time at a predetermined pressure and gas flow rate. Moreover, combination use with conventional heating and stirring is preferable in terms of increasing drying efficiency. The above-mentioned pressure does not need to be particularly high vacuum, and it is sufficient if it is below atmospheric pressure.

The above-mentioned gas may be any gas as long as it is substantially insoluble in water and hydrophobic solvents, such as air, nitrogen, etc.

Further, the flow rate may be at least a level that replaces the volume of the synthesis tank per minute.

The above temperature is below the boiling point of the dispersion medium and the hydrophobic solvent used, and preferably below the glass transition temperature of the binder resin used. For example, toluene is used as the hydrophobic solvent, and the glass transition temperature is 6 as the binder resin.
When using 0℃, the drying temperature is 50~
60°C is optimal.

Note that the stirring speed during this drying does not need to be particularly high, and may be set to a speed that promotes volatilization of the hydrophobic solvent, for example, 10G.
-1100 Orp is preferred.

Dispersion stabilizers are added to the aqueous phase so that oil droplets containing toner components can be stably dispersed in the aqueous phase. Insoluble inorganic salts such as calcium and tricalcium phosphate are used. The content is usually several percent by weight to 10 percent by weight.

(E) Effect According to the present invention, by reducing the pressure of the aqueous system in which oil droplets containing toner components are dispersed or introducing an insoluble gas into the aqueous system, the hydrophobic solvent constituting the oil droplets can be volatilized. At the same time, this volatilized hydrophobic solvent is easily collected.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereby.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

FIG. 1 is a diagram illustrating a toner manufacturing flow using the submerged drying method, and FIGS. 2 and 3 are diagrams illustrating the configuration of an example of a manufacturing apparatus for carrying out the method of the present invention. In FIG. 2, the manufacturing apparatus includes a sealable water tank 1, a water tank 1 containing water 2, oil droplets 3, a homogenizer 4 for mixing and dispersing them, and a stirrer 5. , and a heater 6 for heating the solution in the water tank i. The above aquarium! is provided with a pump 7 for reducing the pressure in the water tank l from its upper part through a communication pipe a, and a cooling trap 8 for collecting the volatilized solvent in the middle of the communication pipe. The cooling trap 8 is cooled by a conventional cooling method such as dry ice, liquid nitrogen, or cold water.

Figure 3 shows a water tank 1 having the same basic configuration as the device in Figure 2.
, the gas inlet section ``0'' and the gas outlet section l! is connected. Here, 9 is a cylinder, b is a gas introduction pipe, C is a gas discharge pipe, and 8 is a cooling trap similar to the above.

” By manufacturing equipment that makes the structure of Yuki 1T!・The method for producing the gel is explained below.

Example 1 First, a styrene-butyl methacrylate copolymer (glass transition temperature = 60°C) as a binder resin, carbon black (particle size 250), nigrosine dye, and polyethylene wax were mixed into Dill methacrylate copolymer 85.5 yen parts carbon black 10 parts nigrosine dye 3 parts by weight polyethylene wax t,
5fflfiffi parts by weight were weighed out and melt-kneaded for 5 minutes.

Thereafter, this kneaded material was cooled and toluene:chloroform-
It was dissolved and dispersed in a mixed solvent having a volume ratio of 4:1 to 10% by weight of the total.

Next, this solution contained 0.5% by weight of gelatin and was heated at 7500 r.
It was dropped into water 2 which was being stirred at high speed by a homogenizer 4 rotating at a high speed of 100 pm, and dispersed into oil droplets 3 having a particle size of 10 μm.

Thereafter, the temperature is raised to 50°C by heating with the heater 6 in the water tank 1, and the system is further heated to 100°C with the pump 7.
Maintained under reduced pressure of mm11g and stirred at 800 rpm with stirrer 5.
111. The solvent was evaporated under stirring. After this, the solid matter was passed through the mouth, washed with water, and dried to obtain an average particle size of 10 μm.
A spherical toner was obtained. The time required for this drying was about 20 minutes. Further, more than 90% of the used amount of solvent was recovered in the trap 8 cooled with liquid nitrogen.

Example 2 Example 2 except that instead of depressurizing with the pump 7, the manufacturing apparatus shown in FIG. In-liquid drying was performed in the same manner as above.

The obtained toner was similar to Example 1, but
The time required was 15 minutes. Moreover, more than 95% of the used amount of solvent was recovered in the trap 8 cooled with liquid nitrogen.

Comparative Example A toner was obtained in the same manner as in the example except that the pressure was not reduced by the pump 7 or the gas was introduced in the above-mentioned submerged drying. The obtained toner was similar to Example 1.2, but it took a long time, about 50 minutes.

(G) Effects of the Invention According to the present invention, in the submerged drying method, by reducing pressure or introducing gas, the solvent can be quickly volatilized and removed, and the solvent can be easily recovered, resulting in cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the manufacturing flow of toner according to the present invention;
FIG. 2 is an explanatory diagram of the configuration of an example of a manufacturing apparatus for implementing the method of the present invention, and FIG. 3 is an explanatory diagram of the configuration of another example of the manufacturing apparatus for implementing the method of the invention. ! ...Water tank, 3..Oil droplets, 5..Agitator, 7..Pump, 9..Gas cylinder, 2.. ...Water, 4...Homogenizer 6...Heater 8...Cooling trap, 0...Gas introduction part, 11... Gas exhaust section.

Claims (1)

[Claims] 1. Preparing a solution of a hydrophobic solvent containing toner components,
A method for producing spherical particles for a toner, which comprises dispersing the particles in the form of oil droplets in an aqueous medium and reducing the pressure of the system to volatilize and remove a hydrophobic solvent to obtain spherical toner particles. 2. Prepare a solution of a hydrophobic solvent containing toner components,
A method for producing spherical particles for toner, which comprises dispersing the particles in the form of oil droplets in an aqueous medium and introducing an insoluble gas into the system to volatilize and remove a hydrophobic solvent to obtain spherical toner particles.