JPH06256406A - Method of suspension polymerization - Google Patents

Abstract

PURPOSE:To provide a method which enables an electrophotographic toner having a sufficient chargeability to be obtained by homogeneously dispersing a charge-controlling agent in a polymer particle. CONSTITUTION:The objective method comprises the step of preparing a liq. suspension contg. polymerizable liq. droplets with desired sizes by putting a disperse phase at least consisting of a monomer compsn. and a compd. of the formula (wherein R1 and R2 are each H, nitro, halogen, alkyl, amino, or carboxyl) and a continuous phase consisting of an aq. medium each into an independent vessel and continuously feeding the two phases each through an independent route at a controlled ratio to a granulator and the step of preparing polymer particle by taking the suspension out of the granulator and introducing the suspension into a polymerizer to complete the polymn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel suspension polymerization method capable of obtaining polymer particles having good chargeability, and more particularly to a suspension polymerization method suitable for producing an electrophotographic toner.

[0002]

2. Description of the Related Art In recent years, the importance of the particle industry utilizing the function of the particles themselves has been increasing, and examples thereof include a gap-maintaining agent, a slipperiness-imparting agent, a functional carrier, and monodisperse particles having surface activity.
It is applied in the field of standard particles, toners, functional fillers that control the fluidity and luster of paints, etc. Although various methods are known for obtaining these particles by a polymerization method, an emulsion polymerization method or a suspension polymerization method is generally used. Among them, the suspension polymerization method according to the prior art employs a method in which a mixed solution including a monomer composition, a polymerization initiator, a colorant and the like is added to an aqueous medium and then suspension polymerization is performed using a disperser. Since the polymer particles to be used are spheres and have excellent fluidity, and further, the manufacturing process is simple and the cost is low, it is proposed to be applied to the manufacture of toner used in, for example, electrophotography. (JP-B-36-10231, JP-B-47-51830, JP-A-57-53756, etc.).

By the way, the chargeability of an electrophotographic toner is usually controlled by dispersing and containing a charge control agent in the toner particles, and the selection of the material is appropriately made according to the system of the copying machine. Is. Hitherto, a nigrosine dye has been known as a charge control agent for controlling the electrophotographic toner to be positively charged. Conventionally, when the electrophotographic toner is manufactured by applying a melt-kneading method in which the dye, the binder resin, the colorant and the like are melt-kneaded at a predetermined mixing ratio and then pulverized, good positive chargeability is obtained. I was able to. However, when an electrophotographic toner containing the dye dispersed therein is produced by the suspension polymerization method according to the above-mentioned conventional technique, the dye cannot be uniformly mixed with the polymer particles as the toner particles and separated. However, there has been a problem that the polymer particles cannot be provided with a good charging property. Further, among the above-mentioned dyes, since materials suitable for suspension polymerization have not been selected, it has been difficult to perform good charge control on the toner by the polymerization method.

[0004]

SUMMARY OF THE INVENTION In the present invention, a charge control agent can be uniformly mixed with polymer particles by combining a compound having a specific structure and a polymerization method, whereby a sufficient positive chargeability can be obtained. The present invention provides a suspension polymerization method capable of obtaining a polymerized toner having

[0005]

The present invention has been made to achieve the above object as a result of intensive studies, and the outline thereof is as follows. The present invention, at least a monomer composition and a disperse phase consisting of a compound represented by the following general formula, and a continuous phase consisting of an aqueous medium, each is held in independent tanks, and through both independent paths, both A step of continuously supplying to the granulator at a controlled ratio to obtain a suspension having polymerizable droplet groups of a desired size, and taking out the suspension from the granulator, And a step of completing the polymerization reaction to obtain polymer particles.

[Chemical 2] (In the formula, R ₁ and R ₂ represent hydrogen, nitro group, halogen group, alkyl group, amino group and carboxyl group)

The suspension polymerization method of the present invention will be described below with reference to the drawings (FIGS. 1 and 2). First, as shown in FIG. 1, a continuous phase tank 1 containing a continuous phase containing a suspension stabilizer as a main component,
Dispersion phase tank 2 containing a dispersion phase containing a monomer composition as a main component
Are simultaneously introduced into the granulator 5 at a constant ratio through the metering pumps 4 and 4, respectively, where a shearing force is applied and the suspension is discharged as a suspension, and the polymerization tank 3 having the condenser 6 is provided.
Then, the required heating is performed by the heating jacket 7 provided around the polymerization tank 3 to complete the polymerization reaction, and a product having a small particle size and a uniform particle size distribution is manufactured. In the present invention, in this case, in particular, a compound having a specific structure is mixed in the dispersion phase tank 2 to obtain polymer particles having sufficient chargeability which cannot be obtained by the conventional technique. Note that one example of the granulator 5 used in the present invention is as shown in FIG. 2, and the granulator 5 has a dispersed phase supply port 14 and a continuous phase supply port 13, and both liquids are in a shear region. Enter 11. A stirring blade 10 is fixed to the shear region 11 by a rotating shaft 8. The stirring blade 10 is rotated by the rotating shaft 8 to generate a suspension in the shear region 11 by a shearing force. A discharge control gap 12 is provided at the edge of the shear region 11, and the dispersion liquid (suspension liquid) that has passed through this gap is discharged from the upper dispersion liquid discharge port 9 and the polymerization tank 3
Is being led to.

As the monomer composition used in the present invention, for example, the following polymerizable monomers capable of polymerization can be used. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Styrene such as dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and the like. Derivatives: Ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; Vinyl acetate, vinyl propionate, vinyl benzoate , Organic acid vinyl esters such as;
Methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate,
Methacrylic acid and its derivatives such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; acrylic acid, methyl acrylate, Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n acrylate
-Acrylic acid and its derivatives such as octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. Vinyl vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl isodol, N-vinyl pyrrolidone; vinyl naphthalenes There are polymerizable monomers such as acrylonitrile, methacrylonitrile, and acrylamide.
These monomers may be used alone or in combination of two or more in various compositions as necessary. It is also possible to disperse other materials in the dispersed phase for the purpose of imparting functionality. Examples of the material include various organic and inorganic pigments such as carbon black, dyes, resin additives,
Examples include organic substances.

In the present invention, the continuous phase is formed by a continuous phase component composed of an aqueous medium. It is preferred to include a suspension stabilizer in the continuous phase. The suspension stabilizer used in the present invention is often a water-soluble polymer having a hydrophilic group and a hydrophobic group in its molecule. The suspension stabilizer has a hydroxyl group as a hydrophilic group, a carboxyl group and a salt thereof, a polar group such as a sulfone group and a salt thereof, and as a hydrophobic group,
It is composed of non-polar groups such as aliphatic and aromatic, and prevents coalescence of the monomer composition particles formed by the granulation step,
It is a compound having the ability to stabilize. Such suspension stabilizers include, for example, polyvinyl alcohol, casein,
Cellulose derivatives such as gelatin, methyl cellulose, methyl hydroxypropyl cellulose and ethyl cellulose, starch and derivatives thereof, poly (meth) acrylic acid and salts thereof are used. In addition, inorganic powders such as calcium phosphate and starch powder silica are often used. During the polymerization, these suspension stabilizers function to coat the surface of the droplets and prevent coalescence and agglomeration of the droplets. Further, a surfactant such as sodium dodecyl sulfonate or sodium dodecylbenzene sulfonate can be added as an auxiliary agent of the suspension stabilizer.

[0009]

EXAMPLES The present invention will be specifically described below based on examples. All percentages in the compounding ratio are% by weight. <Example 1> As a continuous phase, an aqueous solution of polyvinyl alcohol (manufactured by Tokyo Kasei Co., Ltd., polymerization degree: about 2000, saponification degree: about 80%) was prepared in an amount of 1% with respect to water, and sodium sulfate was added with an aqueous solution of 3% in an amount of 3%. It was put in the continuous phase tank 1 shown in FIG. In addition, a mixed solution was prepared by dissolving 15 g of 2,2'-azobisisobutyronitrile in a monomer composition consisting of 4000 g of styrene as a dispersed phase and 1000 g of butyl acrylate, and carbon black (Mitsubishi Kasei M
400 g of A-100) was dispersed. Further, 100 g of a dye containing the compound (1) and the compound (2) shown below was added to this mixed liquid, and the mixture was dispersed for 30 minutes by an ultrasonic disperser. This mixed solution was put into the dispersion phase tank 2 shown in FIG.

[Chemical 3]

[Chemical 4] Next, the dispersed phase (water suspension) was supplied to the granulator 5 at a flow rate of 100 ml / min and the continuous phase at a flow rate of 400 ml / min for 10 minutes. As the granulator 5, one having a rotating part with a diameter of 50 mm was used, and the mixed liquid of the dispersed phase and the continuous phase was stirred under the condition of 10,000 rpm. The dispersion liquid having passed through the granulator 5 was introduced into the polymerization tank 3 shown in FIG. 1 while stirring at 300 rpm with a turbine-type stirring blade, and reacted for 8 hours. Then, the polymer particles were separated by a centrifugal dehydrator, further washed sufficiently with water and then dried to obtain an electrophotographic toner comprising the polymer particles according to the present invention.

Example 2 An electrophotographic toner comprising polymer particles according to the present invention was obtained in the same manner as in Example 1 except that the amount of the dye added was changed to 200 g.

<Comparative Example 1> 200 g of a charge control agent (trade name FCA-201PB, manufactured by Fujikura Kasei Co., Ltd.) which is a styrene acrylic polymer containing a quaternary ammonium salt instead of the compound (1) of Example 1. In the same manner as in Example 1 except that was used, an electrophotographic toner comprising comparative polymer particles was obtained.

<Comparative Example 2> 4000 g of an aqueous solution of polyvinyl alcohol (manufactured by Tokyo Kasei Co., Ltd., polymerization degree of about 2000, saponification degree of about 80%) in water of 1% and sodium sulfate of 3% in water was prepared. Then, the mixture was put in a polymerization tank having a capacity of 10 liters equipped with a jacket whose temperature could be controlled by an electric heater without going through a granulator. Also styrene 80
A mixed solution of 3 g of 2,2′-azobisisobutyronitrile dissolved in a mixed solution of a monomer composition of 0 g and 200 g of acrylic butyl was prepared, and carbon black (manufactured by Mitsubishi Kasei Co., Ltd.) was added to the mixed solution. 80 g of MA-100) was dispersed. Furthermore, the dye 40 in Example 1 was added to this mixed solution.
g was added and dispersed by an ultrasonic disperser for 30 minutes. This mixed solution was placed in the polymerization tank. That is, an aqueous solution of polyvinyl alcohol and a mixed solution of a monomer composition and a dye are placed in a polymerization tank without passing through the process of the present invention shown in FIG. 1 (Homomixer M type, manufactured by Tokushu Kika Kogyo). Equipped with, while stirring at 1000 rpm, the temperature of the reaction solution 8
The temperature was raised to 0 ° C. After maintaining at 80 ° C. for about 3 hours, the number of revolutions of the disperser was set to 1500 rpm, and the reaction was further performed for 5 hours. Thereafter, the polymer particles were separated by a centrifugal dehydrator, further washed sufficiently with water and then dried to obtain an electrophotographic toner composed of comparative polymer particles. When the obtained polymer particles were observed with a microscope, a large number of amorphous fine particles were present in addition to the spherical resin particles. Analysis of these fine particles revealed that the added dye was the main component. That is, this dye is separated without being incorporated in the particles. The particle size distribution also showed a wide particle size distribution ranging from fine particles to coarse particles, and the particle size could not be controlled. Thus, in the conventional suspension polymerization method,
It is difficult to obtain polymer particles incorporating these dyes, and the particle size cannot be controlled.

4 g of polymer particles obtained by the method shown in Examples 1 and 2 and Comparative Examples 1 and 2 and iron powder (FV20 manufactured by Nippon Iron Powder Co., Ltd.)
0-300) and 50 g were put in a 100 cc polyethylene container and hermetically sealed, and then 10 using a ball mill stirrer.
Stir for minutes. After that, the charge amount of the electrophotographic toner composed of polymer particles was measured with a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co.), and the results are shown in Table 1. As is clear from the results in Table 1, the electrophotographic toner comprising the polymer particles produced by the method of the present invention had a sufficient charge amount value on the positively chargeable side as compared with the comparative polymer particles. .

[0014]

[Table 1]

[0015]

According to the suspension polymerization method of the present invention, polymer particles having sufficient chargeability can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a polymerization apparatus used in the present invention.

FIG. 2 is an explanatory diagram showing an example of a granulator used in the present invention.

[Explanation of symbols]

 1 Continuous Phase Tank 9 Dispersion Liquid Discharge Port 2 Dispersion Phase Tank 10 Stirring Blade 3 Polymerization Tank 11 Shearing Area 4 Metering Pump 12 Emission Control Gap 5 Granulator 13 Continuous Phase Supply Port 6 Condenser 14 Dispersed Phase Supply Port 7 For Heating Jacket 8 rotating shaft

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akihiro Sano No. 3 Somune-cho, Shizuoka-shi, Shizuoka Prefecture Tomoegawa Paper Mill Technical Research Institute Co., Ltd. No. 1 Inside the Tagawagawa Paper Mill Technical Research Institute

Claims (1)

[Claims] 1. A dispersion phase comprising at least a monomer composition and a compound represented by the following general formula, and a continuous phase comprising an aqueous medium are held in independent tanks, respectively, and both paths are passed through independent paths. Is continuously supplied to the granulator at a controlled ratio to obtain a suspension having a polymerizable droplet group of a desired size, and the suspension is taken out from the granulator and placed in a polymerization tank. A suspension polymerization method, which comprises the steps of introducing the polymer to complete the polymerization reaction to obtain polymer particles. [Chemical 1] (In the formula, R ₁ and R ₂ represent hydrogen, nitro group, halogen group, alkyl group, amino group and carboxyl group)