JP2597257B2 - 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 function for controlling the fluidity and gloss properties of a gap-retaining agent, a slipping agent, a functional carrier, monodisperse particles having surface activity, standard particles, toner and paint. The present invention relates to a method for obtaining polymerization product particles suitable for use in the particle industry such as a filler, particularly particles having a controlled particle size and particle size distribution. The present invention relates to a suspension polymerization method in which formation of particles is prevented.

[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. However, gap-retaining agents, slipperiness-imparting agents, functional carriers, and surface active materials known as application fields have been increasing. Currently, emulsion polymerization is the main method for obtaining particles for applications such as dispersed particles, standard particles, toner, and functional fillers that control the fluidity and gloss properties of paints by emulsion polymerization. It is. For special applications, soap-free polymerization, dispersion polymerization, seed polymerization, swelling polymerization and the like are also applied. However, these polymerization methods have several disadvantages. For example, it is very difficult to remove non-negligible impurities such as emulsifiers, the particle size of the obtained particles is limited, the cost is extremely high, and the production method is complicated and is not suitable for mass production. There is. Also, in order to obtain particles having a narrow particle size distribution, an emulsion polymerization method is mainly used, but in the emulsion polymerization method, the particle size of the obtained particles is at most about 1 μm at most, and is larger than that. It is extremely difficult to obtain particles of

On the other hand, in the suspension polymerization method, although the obtained polymer is in the form of particles, only those having a nonuniform particle diameter and a wide particle diameter distribution can be obtained. The non-uniformity of the particle size distribution has an important relationship with the properties of the polymer such as mechanical strength, chemical resistance, hue, transparency and moldability, and control of the particle size in the suspension polymerization method is important. It is a problem. That is, the suspension polymerization method is generally a water-soluble inorganic fine particles, a water-soluble polymer, a water-soluble surfactant or the like in the aqueous phase is dissolved or dispersed in the presence of a single or a plurality of dispersion stabilizers, a polymerizable monomer The suspension is prepared by dispersing the base compound, and a polymerization reaction is carried out to obtain polymer particles. At that time, a polymer having a target particle diameter is produced by controlling conditions for producing a suspension, but in order to obtain relatively small particles required for the application as described above, dispersion is required. In the process, it is necessary to apply a high shearing force by a high-speed shearing device such as a homomixer, so that a relatively large amount of so-called artificial emulsified particles is produced by-product. In addition, in order to obtain small particles, since a larger amount of dispersion stabilizer is present in the aqueous phase than in normal suspension polymerization,
In the dispersing step and the polymerization step, a part of the polymerizable monomer tends to be present in the aqueous phase in a large amount. There is a problem that further promotes. Therefore, in the conventional suspension polymerization method, it is inevitable that emulsion particles having a particle size of 1 micron or less are generated when a suspension is prepared, and the yield of the polymer particles required is reduced. Further, when a highly narrow particle size distribution is required, there is a problem that emulsified particles of 1 micron or less as described above are mixed, and particularly, a monodisperse particle having a narrow particle size distribution is used. It is a difficult situation to get. Therefore, establishment of a suspension polymerization technique capable of easily obtaining homogeneous particles has been demanded as an important issue in the field of the particle industry.

[0004]

SUMMARY OF THE INVENTION According to the present invention, it is possible to easily obtain uniform polymer particles having a desired particle size having a narrow particle size distribution, particularly a small particle size, in a suspension polymerization method. An object of the present invention is to provide a suspension polymerization method in which the formation of submicron emulsified particles is prevented.

[0005]

Means for Solving the Problems A first invention of the present invention is:
A suspension having droplets of a desired size is prepared using a polymerizable monomer and an aqueous dispersion containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles. This is a suspension polymerization method in which polymerization is completed to obtain polymer particles. Further, the second invention holds a continuous phase composed of an aqueous medium containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles, and a dispersed phase composed of at least a polymerizable monomer in independent tanks. Supplying the continuous phase and the dispersed phase from the tank to the granulator through independent paths to obtain a suspension having droplets of a desired size; and taking out the suspension from the granulator and performing polymerization. A step of obtaining the polymer particles by conducting the polymerization into a reaction vessel to complete the polymerization.

That is, the present invention is to produce polymer particles by preparing a suspension using an aqueous dispersion containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles and then conducting a polymerization reaction. . As described above, in the first invention, the polymerizable monomer, which is an essential component of the present invention, and an aqueous dispersion containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles are mixed at a predetermined ratio. After preparing a suspension using the aqueous dispersion, the polymerization is completed to obtain polymer particles. At this time, each step of the preparation of the aqueous dispersion, the preparation of the suspension, and the polymerization reaction includes the following steps: a) After the preparation of the aqueous dispersion is performed in an independent tank, the aqueous dispersion is taken out, and the resulting mixture is taken out to a granulator. A method in which the suspension is taken out and fed to a polymerization reaction tank to complete the polymerization, that is, each step is carried out using an independent apparatus. B) Aqueous dispersion After performing the adjustment in an independent tank, a suspension is prepared in the tank, and the suspension is taken out and led to a polymerization reaction tank to complete the polymerization, that is, preparation of an aqueous dispersion. C) preparing an aqueous dispersion in a polymerization reactor, preparing a suspension, and then completing the polymerization of the suspension. In other words, all the steps can be performed in the same tank, etc. It can, in which can be appropriately selected. The aqueous dispersion is obtained by dispersing the three components of the polymerizable monomer, the organic polymerization inhibitor, and the poorly water-soluble inorganic fine particles in water as described above.If necessary, a polymerization initiator, a coloring pigment, other Various additives, suspension stabilizers, auxiliaries and the like depending on the use of the polymer particles can be appropriately added and used.

On the other hand, in the second invention of the present invention, a continuous phase containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles and a dispersed phase containing a polymerizable monomer are previously prepared as described above. That is, an organic polymerization inhibitor and poorly water-soluble inorganic fine particles, and a polymerizable monomer are separately contained, and the continuous phase and the dispersed phase are each directly supplied to a granulator. After the suspension is prepared, the suspension is guided from a granulator to a polymerization reaction tank to complete the polymerization, thereby obtaining polymer particles. Here, the continuous phase is obtained by dispersing the organic polymerization inhibitor and the poorly water-soluble inorganic fine particles in water as described above. If necessary, it is possible to appropriately use additives such as a suspension stabilizer and an auxiliary agent thereof. it can. The disperse phase is at least composed of a polymerizable monomer, and various additives can be used as needed, depending on the use of the polymerization initiator, the coloring pigment, and other polymer particles.

An example of an apparatus for carrying out the second invention of the present invention as described above will be described with reference to the drawings.
As shown in FIG. 1, a continuous phase tank 1 containing a continuous phase and a dispersed phase tank 2 provided with a condenser 6 containing a dispersed phase are supplied to a granulator 5 via a constant-quantity pump 4, 4 at a fixed ratio. At the same time, a shear force is applied to discharge the droplets as a suspension in a certain size range, and the condenser 6
To the polymerization tank 3 provided with the above, and necessary heating is performed by a heating jacket 7 provided around the polymerization tank 3,
The polymerization reaction is completed, and a product having a small particle size and a uniform particle size distribution can be obtained. An example of the granulator 5 used here is as shown in FIG.
The lower portion is provided with a double pipe inner pipe 16 having an inner pipe inlet 19 at the center, and a double pipe outer pipe 17 having an outer pipe inlet 18 around the lower part thereof. To the top. In the center of the upper part, there are a turbine rotating shaft 11, a stirring seal 12, a dispersion liquid discharge port 13, and a bearing 14 and a turbine 15 between the lower part.

In the suspension polymerization method of the present invention, by appropriately controlling the conditions for preparing the suspension, the composition of the aqueous dispersion or the continuous phase / dispersed phase, etc., the weight of a desired particle size, particularly a small particle size, Since coalesced particles can be obtained, and since the continuous phase contains the organic polymerization inhibitor and the poorly water-soluble inorganic fine particles as described above, the formation of emulsified particles of 1 micron or less is prevented. Uniform polymer particles containing almost no micron or less fine particles can be obtained in good yield. The amount of the organic polymerization inhibitor added in the aqueous dispersion and the continuous phase in the present invention is suitably 0.01 to 10% by weight based on the weight of water as a dispersion medium. Here, if it is less than 0.01%, it is difficult to obtain the above-mentioned effects in the present invention, and if it exceeds 10%, polymerization may be inhibited, which is not preferable. Also,
The addition amount of the poorly water-soluble inorganic fine particles is suitably from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, based on the weight of water as a dispersion medium. This is not preferable because of the possibility of the same.

The organic polymerization inhibitor used in the present invention includes, for example, a metal complex compound of a monoazo dye, diphenylpicrylhydrazyl, tri-p-nitrophenylmethyl-N- (3-N-oxyanilino-1,3- Dimethylbutylidene) aniline oxide, p-benzoquinone, p-
tert-butylcatechol, nitrosobenzene, picric acid, dithiobenzoyl disulfide, N, N,
N ', N'-tetraethyl-p-phenylenediamine,
P, P'-difluorodiphenylamine, chloranil and the like. Among them, a metal complex compound of a monoazo dye is preferable, and a metal complex compound of a monoazo dye represented by the following general formula is particularly preferable.

Embedded image In the formula, A and A 'are unsubstituted or substituted phenylene groups, and B and B' are unsubstituted or substituted naphthyl groups. Here, the substituent of the phenylene group and the naphthyl group is not particularly limited, and examples thereof include a halogen, a carboxy group, a sulfonic acid group, a nitro group, an amino group, and an amide group. M represents a metal, for example, Cr, Co, Fe, V, and the like, and R ₁ , R ₂ , R ₃ , and R ₄ represent O and NH .

Examples of the poorly water-soluble inorganic fine particles used in the present invention include inorganic pigments such as calcium phosphate, sodium phosphate, magnesium phosphate, calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, silica and alumina. Is mentioned.

Examples of the polymerizable monomer used in the present invention include the following compounds. Styrene, o-
Methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene,
p-chlorostyrene, 3,4-dichlorostyrene, p-
Ethylstyrene, 2,4-dimethylstyrene, pn-
Butylstyrene, p-tert-butylstyrene, p-
n-hexylstyrene, pn-octylstyrene, p
Styrene and derivatives thereof such as -n-nonylstyrene and pn-decylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride. Vinyl halides; organic acid vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate; Methacrylic acid such as dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like; acrylic acid, methyl acrylate, acrylic Ethyl, n- butyl acrylate,
Isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-acrylate
Ethylhexyl, stearyl acrylate, acrylic acid 2
-Acrylic acid such as chloroethyl and phenyl acrylate and derivatives thereof; 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 N-vinyl compounds such as pyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone;
Vinyl naphthphthalins; acrylonitrile, methacrylonitrile, acrylamide and the like.

The polymerization initiator that can be used in the present invention is preferably soluble in a polymerizable monomer. Examples of such a polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), and 2,2'-azobis-4-methoxy-
2,4-dimethylvaleronitrile, other azo-based or diazo-based polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, and other peroxide-based polymerization initiators. Further, as the coloring pigment, carbon black, various color pigments, and the like can be appropriately used. By adding and polymerizing such a color pigment, it can be easily applied to, for example, the production of an electrophotographic toner.

Next, as the suspension stabilizer which can be used in the aqueous dispersion and the continuous phase in the present invention, a suspension stabilizer generally used in suspension polymerization can be used. A water-soluble polymer having a group and a hydrophobic group 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 is composed of a nonpolar group such as an aliphatic group and an aromatic group as a hydrophobic group. Prevent coalescence of the polymerizable monomer composition particles formed by the suspension preparation process,
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. These suspension stabilizers serve to coat the droplet surface during polymerization and prevent coalescence and agglomeration of the droplets. Further, a surfactant such as sodium dodecylsulfonate and sodium dodecylbenzenesulfonate may be used as an auxiliary of the suspension stabilizer. In addition, neutral salts such as sodium chloride and sodium sulfate may be added to the aqueous dispersion and the continuous phase for the purpose of preventing emulsification. For the purpose of preventing coalescence of the polymerizable monomer composition particles formed in the step of preparing the suspension, a thickener such as glycerin or ethylene glycol may be added.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Example 1 Calcium phosphate 10% aqueous dispersion 50 parts by weight Sodium sulfate 3 parts by weight Sodium dodecylbenzenesulfonate 0.01 part by weight Water 100 parts by weight A dispersion having the above composition was prepared.
An aqueous dispersion (A) is prepared by dispersing 0.1 part by weight of a metal complex compound of a monoazo dye represented by the following structural formula (1) (a mixture of n = 1 and 2) as an organic polymerization inhibitor with respect to 00 parts by weight. Was adjusted.

Embedded image On the other hand, a solution prepared by dissolving 15 g of 2,2'-azobisisobutyronitrile in a mixed solution of 4000 g of styrene as a polymerizable monomer and 1000 g of butyl acrylate was prepared, and carbon black (Mitsubishi Chemical) MA-10
0) A dispersion (B) in which 400 g was dispersed was obtained. 4000 g of the above aqueous dispersion (A) and 1000 g of the dispersion (B)
Were placed in a stainless steel container having a capacity of 10 liters, and were dispersed at 10,000 rpm for 20 minutes using a granulator made of a homomixer M type (manufactured by Tokushu Kika Kogyo Co., Ltd.). The suspension produced by the granulator was placed in a reactor equipped with a heating jacket of 10 liters of hot water and reacted at 80 ° C. for 8 hours while stirring the turbine-type stirring blade at 200 rpm. Thereafter, the reaction solution was separated by filtration to obtain polymer particles, and the particles were sufficiently washed with 3% nitric acid and water.
The polymer was dried under reduced pressure at 0 ° C. for 12 hours to obtain polymer particles obtained by the suspension polymerization method of the present invention.

Example 2 Example 1 was repeated except that the compound of the following structural formula (2) was used as the metal complex compound of the monoazo dye.
In the same manner as described above, polymer particles obtained by the suspension polymerization method of the present invention were obtained.

Embedded image Example 3 In the polymerization apparatus shown in FIG. 1, the aqueous dispersion (A) in Example 1 was placed in a continuous phase tank, and the dispersion (B) was placed in a dispersion phase tank. Next, the dispersed phase was fed to the granulator at 100 ml / min and the continuous phase at 40 ml / min for 10 minutes. The granulator was operated at 10,000 rpm using the granulator shown in FIG. The suspension passed through the granulator was guided into the polymerization tank shown in FIG. 1 while being stirred at 300 rpm by a turbine-type stirring blade, and reacted for 8 hours. Thereafter, the reaction solution was separated by filtration to obtain polymer particles. After the particles were sufficiently washed with 3% nitric acid and water, the particles were dried under reduced pressure at 40 ° C. for 12 hours to obtain polymer particles obtained by the suspension polymerization method of the present invention. I got

Comparative Example 1 Comparative polymer particles were obtained in the same manner as in Example 1 except that the metal complex compound of the monoazo dye was not used. Comparative Example 2 Comparative polymer particles were obtained in the same manner as in Example 3 except that the metal complex compound of the monoazo dye was not used. Examples 1 to 3 and Comparative Examples 1 and 2 above
The results of measuring the particle size distribution of the polymer particles obtained in the above with a Microtrac particle size analyzer (manufactured by Nikkiso Co., Ltd.) are as shown in FIGS. 3 and 4, and the polymer particles obtained by the suspension polymerization method of the present invention It was confirmed that no fine particles of 1 micron or less were generated and the particle size distribution was narrow.

[0018]

The suspension polymerization method of the present invention has a very narrow particle size distribution that does not contain fine particles because it can prevent the formation of emulsified particles of 1 micron or less that are formed in suspension. It has an excellent effect that polymer particles can be obtained. In addition, small particles on the order of microns can be obtained without containing fine particles of 1 micron or less, so that they are expected to be used as highly functional particles in various fields including electrophotographic toners.

[Brief description of the drawings]

FIG. 1 is an example of a polymerization apparatus used in the suspension polymerization method of the present invention.

FIG. 2 is an example of a granulator used in the suspension polymerization method of the present invention.

FIG. 3 is a graph showing the particle size distribution of polymer particles obtained in Example 1, Example 2, and Comparative Example 1 of the present invention.

FIG. 4 is a graph showing the particle size distribution of polymer particles obtained in Example 3 and Comparative Example 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous phase tank 2 Dispersion phase tank 3 Polymerization tank 4 Metering pump 5 Granulator 6 Condenser 7 Heating jacket 11 Turbine rotating shaft 12 Stirring seal 13 Dispersion liquid discharge port 14 Bearing 15 Turbine 16 Double pipe inner pipe 17 Double pipe Outer pipe 18 Outer pipe inlet 19 Inner pipe inlet 20 Flange for opening diameter adjustment

Claims (3)

(57) [Claims] 1. A suspension having droplets of a desired size is prepared by using a polymerizable monomer and an aqueous dispersion containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles. A suspension polymerization method comprising completing polymerization of the suspension to obtain polymer particles. 2. A continuous phase comprising an aqueous medium containing an organic polymerization inhibitor and poorly water-soluble inorganic fine particles, and a dispersed phase comprising at least a polymerizable monomer are held in independent tanks, respectively. Supplying the continuous phase and the dispersed phase to the granulator through independent paths to obtain a suspension having droplets of a desired size, and taking out the suspension from the granulator, And completing the polymerization to obtain polymer particles. 3. The suspension polymerization method according to claim 1, wherein the organic polymerization inhibitor is a metal complex compound of a monoazo dye represented by the following general formula. Embedded image (Wherein A and A 'are unsubstituted or substituted phenylene groups, B and B' are unsubstituted or substituted naphthyl groups. M represents a metal, R ₁ , R
₂ , R ₃ and R ₄ represent O and NH . )