JP3248747B2 - Suspension polymerization method - Google Patents

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 particles themselves has been increasing. For example, a gap-retaining agent, a slip imparting agent, a functional carrier, monodisperse particles having surface activity,
It is applied in the fields of standard particles, toners, and functional fillers for controlling the flowability and gloss properties of paints. Various methods are known for obtaining these particles by a polymerization method. Generally, an emulsion polymerization method or a suspension polymerization method is used. Among these, the suspension polymerization method according to the prior art employs a method in which a mixed solution composed of a monomer composition, a polymerization initiator, a colorant, etc. is added to an aqueous medium and then subjected to suspension polymerization using a dispersing machine. Since the polymer particles obtained are spherical and have excellent fluidity, and the manufacturing process is simple and the cost is low, it is proposed to apply the method to the production of toner used in, for example, electrophotography. (JP-B-36-10231, JP-B-47-51830, JP-A-57-53756, etc.).

[0003] By the way, in an electrophotographic toner, the chargeability is usually controlled by dispersing and containing a charge control agent in toner particles, and the material selection is appropriately performed according to the system of the copying machine. It is. Conventionally, a complex compound of salicylic acid and a metal has been known as a charge control agent for controlling an electrophotographic toner to have a negative chargeability. Conventionally, when a complex compound and a binder resin, a colorant, and the like are applied to a melt-kneading method in which hot-melt kneading is performed at a predetermined mixing ratio and then pulverized to produce an electrophotographic toner, good negative chargeability is obtained. I got it. However, when an electrophotographic toner in which the complex compound is dispersed and contained is to be manufactured by the above-mentioned conventional suspension polymerization method, the complex compound cannot be uniformly mixed with the polymer particles as the toner particles and separated. As a result, a problem arises in that good chargeability cannot be given to the polymer particles. In addition, since a material suitable for suspension polymerization has not been selected among complex compounds, it has been difficult to perform good charge control on toner by a polymerization method.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a charge controlling agent can be uniformly mixed with polymer particles by combining a complex compound having a specific structure with a polymerization method, whereby a sufficient negative charge can be obtained. An object of the present invention is to provide a suspension polymerization method capable of obtaining a polymerized toner having properties.

[0005]

SUMMARY OF THE INVENTION 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 dispersed phase composed of the monomer composition and the compound represented by the following general formula, and a continuous phase composed of an aqueous medium, each in an independent tank, and through each independent path, both of them, Stirring rotated by a rotating shaft continuously at a controlled ratio
Shear area with wings and emission control gaps at the edges
Fed through a granulator having, obtaining a suspension having a polymerizable droplets group having a desired size, remove the suspension from the granulated machine, the leading polymerization reaction in the polymerization vessel And obtaining a polymer particle by completing the suspension polymerization method.

Embedded image (Wherein, R ₁ and R ₂ represent hydrogen, a nitro group, a halogen group, an alkyl group, an amino group, or a carboxyl group, and M ₁ represents Z
n represents Fe, Ni, Co, Cr, X represents hydrogen, sodium, potassium, an organic ammonium salt, and n represents 1 to
4)

Hereinafter, the suspension polymerization method of the present invention will be described 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,
Dispersed phase tank 2 containing a dispersed phase mainly composed of a monomer composition
Are simultaneously introduced into the granulator 5 at a constant ratio via the metering pumps 4, 4, respectively, where a shearing force is applied to discharge the suspension as a suspension, and the polymerization tank 3 provided with the condenser 6.
Then, necessary heating is performed by a 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 produced. In the present invention, in this case, in particular, by mixing a compound having a specific structure in the disperse phase tank 2, polymer particles having a sufficient chargeability, which cannot be obtained by the prior art, are obtained. The granulator 5 used in the present invention is as shown in FIG. 2. The granulator 5 has a dispersed phase supply port 14 and a continuous phase supply port 13, and both liquids are in the shear region 1
Enter 1. The stirring blade 10 is fixed to the shearing region 11 by the rotating shaft 8. The stirring blade 10 is rotated by the rotation shaft 8 and generates a suspension in the shearing region 11 by the shearing force. At the edge of the shearing region 11, a discharge regulating gap 12 is provided.
Is provided, and the dispersion (suspension) passing through the gap is discharged from the dispersion discharge outlet 9 on the upper side, and is guided to the polymerization tank 3.

[0007] As the monomer composition used in the present invention, for example, the following polymerizable monomers 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- Styrenes such as dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and the like Derivatives; Ethylene unsaturated olefins such as ethylene, propylene, butylene, isobutylene, etc .; 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 such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like; 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 and phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether 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 and N-vinyl pyrrolidone; vinyl naphthalenes A polymerizable monomer such as acrylonitrile, methacrylonitrile, and acrylamide;
These monomers are used alone or, if necessary, in combination of two or more kinds in various compositions. In addition, other materials can be dispersed in the dispersed phase for the purpose of imparting functionality. As its material, for example, various organic and inorganic pigments such as carbon black, dyes, resin additives,
Organic substances and the like can be mentioned.

[0008] In the present invention, the continuous phase is formed by a continuous phase component composed of an aqueous medium. The continuous phase preferably contains a suspension stabilizer. As the suspension stabilizer used in the present invention, a water-soluble polymer having a hydrophilic group and a hydrophobic group in its molecule is often used. The suspension stabilizer has a polar group such as a hydroxyl group, a carboxyl group and a salt thereof, a sulfone group and a salt thereof as a hydrophilic group, and 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 that has the ability to stabilize. Such suspension stabilizers include, for example, polyvinyl alcohol, casein,
Cellulose derivatives such as gelatin, methylcellulose, methylhydroxypropylcellulose, and ethylcellulose, starch and its derivatives, poly (meth) acrylic acid, and salts thereof are used. The calcium phosphate to other inorganic powders such as fine powder silica is also often used. These suspension stabilizers serve to coat the droplet surface during polymerization to prevent coalescence and agglomeration of the droplets. Further, a surfactant such as sodium dodecylsulfonate, sodium dodecylbenzenesulfonate and the like can be added as an auxiliary of the suspension stabilizer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. In addition, all percentages of the mixing ratio are weight%. <Example 1> As a continuous phase, an aqueous solution of polyvinyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd., degree of polymerization: about 2000, degree of saponification: about 80%) of 1% with respect to water and sodium sulfate with 3% with respect to water was prepared. , In the continuous phase tank 1 shown in FIG. Also, a mixed solution was prepared by dissolving 15 g of 2,2'-azobisisobutyronitrile in a monomer composition comprising 4000 g of styrene and 1000 g of butyl acrylate as the dispersed phase, and carbon black (Mitsubishi) Kaseisha M
A-100) 400 g was dispersed. Further, 200 g of the compound (1) shown below was added to the mixed solution, and the mixture was dispersed by an ultrasonic disperser for 30 minutes. This mixture was placed in the dispersed phase tank 2 shown in FIG.

Embedded image Next, the dispersed phase (aqueous suspension) was supplied to the granulator 5 at a flow rate of 100 ml / min, and the continuous phase was supplied at a flow rate of 400 ml / min for 10 minutes. The granulator 5 having a rotating part with a diameter of 50 mm was used, and the mixture of the dispersed phase and the continuous phase was stirred at 10,000 rpm. The dispersion passed through the granulator 5 was guided into the polymerization tank 3 shown in FIG. 1 while being stirred at 300 rpm by a turbine type stirring blade, and reacted for 8 hours. Thereafter, the polymer particles were separated by a centrifugal dehydrator, washed sufficiently with water, and dried to obtain an electrophotographic toner comprising the polymer particles according to the present invention.

<Example 2> An electrophotographic toner comprising the polymer particles according to the present invention was prepared in the same manner as in Example 1 except that the following compound (2) was used in place of the compound (1) of Example 1. Obtained.

Embedded image

Example 3 An electrophotographic toner comprising the polymer particles according to the present invention was prepared in the same manner as in Example 1 except that the compound (3) shown below was used instead of the compound (1) of Example 1. Obtained.

Embedded image

Comparative Example 1 A charge control agent comprising a styrene-based polymer having an acidic group instead of the compound (1) of Example 1 (FCA-1001N, manufactured by Fujikura Kasei Co., Ltd.)
An electrophotographic toner composed of comparative polymer particles was obtained in the same manner as in Example 1 except that 200 g was used.

<Comparative Example 2> 4000 g of an aqueous solution of polyvinyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd., degree of polymerization: about 2,000, degree of saponification: about 80%) in water at 1% and sodium sulfate in water at 3% in water was prepared. The mixture was directly placed in a polymerization tank having a capacity of 10 liters equipped with a jacket capable of controlling the temperature by an electric heater without passing through a granulator. Styrene 80
A mixture of 3 g of 2,2′-azobisisobutyronitrile dissolved in a mixture of a monomer composition consisting of 0 g and 200 g of acrylic butyl was prepared, and carbon black (manufactured by Mitsubishi Chemical Corporation) was added to the mixture. MA-100) was dispersed. Further, 40 g of the compound (1) in Example 1 was added to the mixture, and the mixture was dispersed by an ultrasonic disperser for 30 minutes. This mixture was placed in the polymerization tank. That is, an aqueous solution of polyvinyl alcohol and a mixed solution of the monomer composition and the compound (1) are placed in a disperser (Homomixer M type, Tokushu Kika Kogyo Co., Ltd.) without going through the process of the present invention shown in FIG. The reaction solution was heated to 80 ° C. while stirring at 1000 rpm. After holding at 80 ° C. for about 3 hours, the disperser was rotated at 1500 rpm,
The reaction was continued for another 5 hours. Thereafter, the polymer particles were separated by a centrifugal dehydrator, washed sufficiently with water, and dried to obtain an electrophotographic toner composed of comparative polymer particles. Observation of the obtained polymer particles with a microscope revealed that a large number of irregular fine particles existed in addition to the spherical resin particles. Analysis of these fine particles revealed that the added compound (1) was the main component. That is, this compound is separated without being taken into 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 compounds, and the particle diameter cannot be controlled.

4 g of the polymer particles obtained by the methods shown in Examples 1 to 3 and Comparative Examples 1 and 2 and iron powder (FV20 manufactured by Nippon Iron Powder Co., Ltd.)
0-300) was sealed in a 100 cc polyethylene container, and then sealed with a ball mill stirrer.
Stirred for minutes. Thereafter, the charge amount of the electrophotographic toner composed of polymer particles was measured by a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd.), and the results are shown in Table 1. As is evident from the results in Table 1, the electrophotographic toner comprising the polymer particles according to the production method of the present invention had a sufficient charge amount on the negatively chargeable side as compared with the comparative polymer particles. .

[0015]

[Table 1]

[0016]

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

[Brief description of the drawings]

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

FIG. 2 is an explanatory view showing a granulator used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous phase tank 9 Dispersion liquid discharge port 2 Dispersion phase tank 10 Stirring blade 3 Polymerization tank 11 Shear area 4 Metering pump 12 Discharge regulating gap 5 Granulator 13 Continuous phase supply port 6 Condenser 14 Dispersed phase supply port 7 Heating Jacket 8 axis of rotation

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshiya Matsushita 3-1, Yomune-cho, Shizuoka-shi, Shizuoka Pref. Inspector in the Technical Research Laboratory of Hamakawa Paper Mills Kunihiko Sato (56) References JP-A-3-247601 (JP, A) JP-A-59-64850 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00-2/50

Claims (1)

(57) [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, and are respectively passed through independent paths. Agitating blades that are continuously rotated by a rotating shaft at a controlled ratio , and discharge
Supplying to a granulator having a shearing region provided with a control gap, a step of obtaining a suspension having a polymerizable droplet group of a desired size, and removing the suspension from the granulator, A step of obtaining polymer particles by introducing the mixture into a polymerization tank to complete the polymerization reaction. Embedded image (Wherein, R ₁ and R ₂ represent hydrogen, a nitro group, a halogen group, an alkyl group, an amino group, or a carboxyl group, and M ₁ represents Z
n represents Fe, Ni, Co, Cr, X represents hydrogen, sodium, potassium, an organic ammonium salt, and n represents 1 to
4)