JPH03244603A - Process and apparatus for polymerization - Google Patents

Abstract

PURPOSE:To facilitate the formation of a latex with a low content of coarse particles in good controllability of reaction by feeding a monomer having a polymerizable double bond and/or assistants under the surface of the liquid phase of the polymerization system. CONSTITUTION:A process for performing the emulsion polymerization or fine suspension polymerization of a monomer having a polymerizable double bond (or a mixture thereof), wherein the monomer and/or the assistants are ded under the surface of the liquid phase of the polymerization reaction system. The above feeding can provide good controllability of polymerization when compared with the conventional process wherein the feeding is performed through a nozzle open to the vapor phase of the polymerization system, so that the content of coarse particles in the formed polymer emulsion can be markedly decreased. Examples of the monomers which can be particularly desirably used in the polymerization include vinyl chloride and a monomer mixture based thereon.

Description

Detailed Description of the Invention (a) Object of the Invention (Field of Industrial Application) The present invention provides a polymer emulsion (latex) with good reaction controllability and a low content of coarse polymer particles. The present invention relates to an emulsion polymerization method or a fine suspension polymerization method for monomers having polymerizable double bonds, and a polymerization apparatus used for the polymerization.

(Prior art) Conventionally, in the emulsion polymerization method or the fine suspension polymerization method, monomers and auxiliary agents added to the polymerization reaction system are added all at once before the start of polymerization in order to control the polymerization reaction. In addition to addition, it can be added in various ways during the polymerization reaction (including additional additions; the same applies hereinafter).
be done. For example, various auxiliary agents may be added all at once or in portions during the polymerization reaction, or may be added continuously for a certain period of time.

However, conventionally, auxiliary agents were added to the reaction system during the polymerization reaction through a nozzle that opened into the gas phase existing above the liquid phase of the polymerization reaction system in the polymerization reactor.

The term "auxiliary agents" as used herein is a general term for components other than monomers that are added to the polymerization reaction system, such as polymerization initiators, surfactants, molecular weight regulators, and the like.

In addition, polymer emulsions (latex) obtained by polymerization reactions using conventional emulsion polymerization methods or fine suspension polymerization methods inevitably contain a certain amount of coarse polymer particles.
Moreover, if the coarse particles are mixed in, it may cause streaks during processing.
Since these coarse particles cause problems such as generation of particles and poor dispersion, it is necessary to remove the coarse particles by methods such as filtration and pulverization. However, the filtration method increases the number of steps and reduces processing and yield of furnace slag, while the pulverization method increases the number of steps and deteriorates the quality due to the contamination of unpulverized materials.

(Spirit of the Invention) The present invention provides an emulsion polymerization method or a fine suspension polymerization method that has good reaction controllability and can easily produce a polymer emulsion containing a small amount of coarse particles, and It is an object of the present invention to provide a polymerization apparatus that can be advantageously used in legal practice.

(b) Structure of the invention (means for solving the problem) The polymerization method of the present invention comprises a monomer having a polymerizable double bond (
In the method of emulsion polymerization or fine suspension polymerization of monomers (containing a mixture of the same monomers), the supply of monomers and/or auxiliaries to the polymerization reaction system during the polymerization reaction is This method is characterized in that it is carried out by adding subsurface.

Further, the polymerization apparatus of the present invention is a polymerization reactor in which a monomer having a polymerizable double bond (including a mixture of the same monomers) is subjected to emulsion polymerization or fine suspension polymerization. This apparatus is characterized in that a supply pipe for supplying monomers and/or auxiliary agents to the polymerization reactor is configured to open below the liquid level of the liquid phase of the reaction system in the polymerization reactor.

In the present invention, monomers and/or auxiliaries are thus supplied to the polymerization reaction system during the polymerization reaction by adding them below the liquid surface of the liquid phase of the polymerization reaction system.
Compared to the conventional method in which these substances are supplied through a nozzle that opens into the gas phase of the polymerization reaction system, the controllability of the polymerization reaction is improved, and the amount of coarse particles mixed into the produced polymer emulsion can be significantly reduced. It can be reduced.

The monomer used in the polymerization of the present invention is a monomer having a polymerizable double bond, or a mixture of two or more of the same monomers. Specific examples of the monomer include halogenated vinyl monomers such as vinyl chloride and vinylidene chloride;
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl stearate, monounsaturated acids such as acrylic acid, methacrylic acid, itaconic acid, alkyl esters of these unsaturated acids, methyl vinyl ether, ethyl vinyl ether, octyl Vinyl ethers such as vinyl ether and lauryl vinyl ether, divalent unsaturated acids such as maleic acid and fumaric acid, acid anhydrides of these divalent unsaturated acids, alkyl esters of these divalent unsaturated acids, and aromatic vinyl such as styrene. Examples include compounds, unsaturated nitriles, etc. This polymer is vinyl chloride and a monomer mixture containing vinyl chloride as a main component.

Examples of the polymerization initiator used in the polymerization of the present invention include persulfates (sodium salts, potassium salts, ammonium salts, etc.), water-soluble peroxides such as hydrogen peroxide, or these and a reducing agent. (e.g. sodium sulfite, sodium pyrosulfite, ammonium sulfite, sodium bisulfite, ascorbic acid, sodium formaldehyde sulfoxylate, etc.), azobisisobutyronitrile, azobis-24-
dimethylvaleronitrile, lauroyl peroxide,
An initiator consisting of a monomeric soluble (oil-soluble) initiator such as t-butyl peroxypivalate, or a combination of these oil-soluble initiators and a reducing agent similar to the reducing agent for the redonx initiator described above. etc. can be mentioned.

Examples of emulsifiers used in the polymerization of the present invention include higher alcohol sulfate ester salts (alkali metal salts, ammonium salts), alkylbenzene sulfonates (alkali metal salts, annonionic surfactants, and cationic surfactants). One type of these surfactants may be used, or two or more types may be used in combination.Anionic surfactants are particularly preferred.

In addition, examples of the polymerization degree regulator used in the polymerization of the present invention include trichlorethylene, carbon tetrachloride,
- Chain transfer agents such as mercaptoethanol and octyl mercaptan, and crosslinking agents such as diallyl phthalate, triallyl isocyanurate, ethylene glycol diacrylate, and trimethylolpropane trimethacrylate.

In addition to the above, examples of auxiliaries used in the polymerization of the present invention include water-soluble filtrate metal salts such as cupric chloride, condensed ferrous sulfate, and nickel nitrate; Examples include alkali metal salts of acids, pH4Jl regulators such as potassium hydrogen phthalate, and sodium hydrogen carbonate.

As mentioned above, the feature of the polymerization method of the present invention is that these monomers and/or auxiliaries are supplied to the reaction system during the polymerization reaction by adding them below the liquid surface of the liquid phase of the polymerization reaction system. The polymerization method of the present invention has been improved so that the polymerization reaction is carried out by a method in which the polymerization reaction is carried out, and therefore, compared to the conventional method in which the polymerization is supplied through a nozzle opened to the gas phase of the polymerization reaction system, the polymerization method of the present invention has improved controllability of the polymerization reaction. As a result, a polymer emulsion containing significantly less coarse particles can be easily obtained.

1 and 2 of the accompanying drawings illustrate a polymerization apparatus suitable for use in carrying out the polymerization method of the present invention.

In the apparatus shown in FIG. 1, each nozzle 8 of the supply pipes 3, 4, and 5 for supplying monomers and auxiliary agents to the polymerization reactor 1 during the polymerization reaction is connected to the normal liquid level of the polymerization reactor 1. It is designed to be submerged far below.

In addition, in the apparatus shown in FIG. 2, the supply pipe 6 for supplying monomers and auxiliaries to the polymerization reactor 1 during the polymerization reaction is located far below the normal liquid level of the polymerization reactor 1. The nozzle 8 of another supply pipe 7 is opened in the side wall and is configured to be submerged far below the normal liquid level of the polymerization reactor 1.

Note that the monomer and auxiliary agent supply pipes 3, 4, 5, and 7 shown in FIGS. 1 and 2 are constructed to be submerged below the liquid level for regular use, so Since there is a risk of breakage due to vibrations caused by stirring by the machine 2, it is necessary to protect it using appropriate fixing means. As detailed in FIG. 3, the supply tubes 4 and 5 of FIG. 1 are protected by securing them to the baffle 9 with mating retainers IO. The supply pipe 3 in FIG. 1 and the supply pipe 7 in FIG. 2 are also fixed and protected by appropriate fixing means, but the illustration of the fixing means is omitted to simplify the drawings.

(Examples, etc.) The following is a more detailed explanation of Examples and Comparative Examples.

Example 1 (Preparation of seed polymer) A 35-volume polymerization tank having the structure shown in Fig. 1 was heated at 54°C.
18 t of deionized water, 1 kg of potassium persulfate, and 5 kg of sodium pyrosulfite were added and stirred for about 20 minutes to dissolve. Next, the pressure inside the polymerization tank was reduced to 610 mmHg and maintained at 55°C for 50 minutes.

Next, 3 tons of vinyl chloride monomer was charged into the same tank at once, and the temperature inside the tank was raised to 50"C. After 15 minutes had passed after the monomer was charged, the pre-dissolved There were 0, 2
A wt % potassium persulfate aqueous solution was gradually added at a rate of about iN/min through the supply pipe 4, and thereafter the addition rate of the potassium persulfate aqueous solution was adjusted so as to maintain a constant polymerization rate. Made it react. In addition, from the time the polymerization rate reached 10%, 9t of vinyl chloride monomer was added at a rate of 1.8t/h.
The monomers were continuously charged from the supply pipe 3 at a ratio of r. Note that the polymerization rate described in this specification means the polymerization rate with respect to all the monomers charged. Furthermore, from the time when the polymerization rate reached 15%, the supply of a separately dissolved approximately 5% by weight sodium lauryl sulfate aqueous solution was started using the supply pipe 5 at a rate of 8N/10 minutes. Total amount of added sodium is 80k
It was added continuously until the amount reached 100 g. The reaction was stopped when the pressure inside the tank dropped by 2.0 kg/aa from the saturation pressure of vinyl chloride monomer at 50°C, and the unreacted monomer was collected to obtain a seed polymer latex. .

This latex had monodispersed particles with a particle size of about 0.52 μm, and the stability of the latex was good. 100 mj of this latex! Samples were collected up to the upper limit of the scale on a mesh ring, and the amount of sedimentation after standing for 4 hours was measured and determined as the amount of coarse particles.The amount was Imj! Met. Furthermore, in order to confirm reproducibility, the same polymerization reaction as above was carried out twice.
The amount of sedimentation of the obtained latex was measured and found to be 2 mff1 and 1 ml, respectively.

(Two-stage emulsion polymerization) In a polymerization tank having the same structure as that used for preparing the seed polymer described above, 18 tons of deionized water and 700 kg of the seed polymer latex prepared as described above (thread diameter 0.52μ) were added. After charging 9 kg of sodium formaldehyde sulfoxylate (based on solid content), 1.5 kg of sodium trihydrogen phosphate, and 10 kg of a 0.03% by weight cupric chloride aqueous solution, the inside of the tank was degassed. 3.5 t of vinyl chloride monomer was charged therein, and the temperature was raised to 55°C.

Next, a 0.2% by weight aqueous solution of 5 kg of hydrogen peroxide was continuously added to the lower part of the liquid phase through the supply pipe 4 while controlling the addition rate to maintain a constant polymerization rate. From the time when the polymerization rate of the charged monomers reaches 10% until the end of polymerization, 90 kg of 0.6% by weight sodium lauryl sulfate aqueous solution as sodium lauryl sulfate is continuously added to the polymerization reaction system from the supply pipe 5. It was added below the liquid phase. 1. from the saturation pressure of vinyl chloride monomer when the internal pressure of the polymerization tank is 55°C.
The point at which the reaction has dropped by 0 kg/cm is considered to be the completion point of the reaction.
Unreacted monomers were collected, and latex with an average particle size of 0.92 μm was obtained in a yield of 84%.

When this latex was subjected to the same sedimentation test (measuring the amount of coarse particles) as in the preparation of the seed polymer described above, the amount of sedimentation was 3 mj! Met.

Comparative Example 1 A conventional polymerization tank was used in which the nozzles of the supply pipes for supplying monomers and auxiliaries were all opened to the gas phase at the top of the polymerization tank, and a potassium persulfate aqueous solution and a sodium lauryl sulfate aqueous solution were vaporized. It is supplied from a nozzle opened in the phase part,
Other than that, polymerization was carried out in the same manner as in the preparation of the seed polymer in Example 1. The polymerization was carried out three times in total, and each latex obtained was subjected to the same sedimentation test as above, and the amount of sedimentation was 12 tsj! , 15
mj! and 9 ml.

(Two-stage emulsion polymerization) Using the same conventional polymerization tank as used in the preparation of the seed polymer in Comparative Example 1, hydrogen peroxide, vinyl chloride monomer, and sodium lauryl sulfate aqueous solution were all reacted. Added to the gas phase above the tea liquid phase, otherwise the same as Example 1
Polymerization was carried out in the same manner as the two-stage emulsion polymerization. The obtained latex had approximately the same average particle size and reaction rate as in Example 1, but the sedimentation amount of the latex was 20 ml, which was significantly larger than in Example 1.

Example 2 (Preparation of finely suspended seed polymer) 200 g of irauryl alcohol was added to a 2001 volume premixing tank equipped with a stirrer, and then the inside of the premixing tank was degassed, and then vinyl chloride monomer was added. 60 kg was added and maintained at 35° C. with stirring. After stirring uniformly, use an emulsifier (homogenizer) to obtain the desired droplet diameter (
After completing the transfer of the zero dispersion liquid, which was transferred to a reaction tank with a volume of 200 I2 equipped with a stirrer and which had been degassed in advance, the temperature of the reaction tank was adjusted. The temperature was raised and polymerization was carried out using a known method. The obtained latex is
The average particle size was 0.56μ.

(Two-stage fine suspension polymerization) 80 kg of deionized water was added to a polymerization tank having a volume of 2,001 cm and the structure shown in FIG. Seed latex 5kg
(solid content equivalent), 0.05fi amount% ferrous chloride aqueous solution 1
After charging 00 g of sodium bicarbonate and 20 g of sodium hydrogen carbonate, the inside of the tank was degassed, and 25 kg of vinyl chloride monomer was charged from a supply pipe (not shown), and the temperature was raised to 47°C.

Next, a 0.5% by weight aqueous solution of sodium formaldehyde sulfoxylate, which had been dissolved in advance, was added at a rate of about 4f/h.
It was continuously added to the liquid phase of the polymerization reaction system through the supply pipe 6 at a ratio of r to initiate heavy crystals, and the amount added was adjusted so as to obtain a constant reaction rate during the polymerization A reaction. In addition, from the time when the reaction rate of the vinyl chloride monomer charged at once reached 7 to 8%, the vinyl chloride monomer 3
5 kg was continuously added to the gas phase of the polymerization reaction system from a supply pipe (not shown) at a rate of 8 kg/hr, and from the time when the polymerization rate reached 10% until the end of the polymerization reaction. Then, an approximately 8% by weight aqueous sodium dodecylbenzenesulfonate aqueous solution (total of 5f) prepared separately as an emulsifier was added to lj! from the supply pipe 7. /hr, the pressure in the polymerization tank was 1.5 kg/cm from the saturation pressure of vinyl chloride at 47°C.
``When it fell, the polymerization was stopped and the unreacted monomer was collected.

The obtained latex had an average particle size of 1.2 μm, a reaction rate of 80%, and a sedimentation amount of the latex measured in the same manner as described above was 2 ml.

Comparative Example 2 Same as Example 2 except that the addition of hydrogen perchloride and the aqueous solution of sodium dodecylbenzenesulfonate were carried out using a nozzle into the gas phase existing above the liquid phase of the polymerization reaction system. and polymerized. The average particle size of the obtained latex was 1.3 μm, and the reaction rate was about 82%, but the amount of sedimentation of the latex measured in the same manner as above was 18 μl.

Comparison between Example 1 and Comparative Example 1, and Example 2 and Comparative Example 2
As is clear from the comparison, the polymer emulsion (latex) obtained in the example is a stable latex with a significantly low content of coarse particles.

(c) Effects of the Invention The polymerization method of the present invention has good controllability of the reaction, and a stable polymer emulsion (latex) with a significantly low content of coarse particles can be easily obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal sectional schematic diagrams illustrating a polymerization apparatus suitable for carrying out the polymerization method of the present invention. Also,
FIG. 3 is an enlarged partial longitudinal sectional view of FIG. 1. Each symbol in the figure indicates the following. 1... Polymerization reactor 2... Stirrer 3.4, 5, 6.7... Supply pipe 8... Supply pipe nozzle 9... Panfur 10... Matching holder L...・Reactor normal liquid level Figure 1 Figure 2 Figure 3

Claims (6)

[Claims] (1) In a method of emulsion polymerization or fine suspension polymerization of a monomer having a polymerizable double bond (including a mixture of the same monomers), the monomer and/or A polymerization method characterized in that auxiliaries are supplied by adding them below the liquid surface of a liquid phase portion of a polymerization reaction system. (2) The supply of monomers and/or auxiliaries during the polymerization reaction is
The polymerization method according to claim 1, wherein the polymerization method is carried out by adding at a plurality of locations below the liquid surface of the liquid phase portion of the polymerization reaction system. (3) The polymerization method according to claim 1 or 2, wherein the monomer having a polymerizable double bond is vinyl chloride or a monomer mixture containing vinyl chloride as a main component. (4) In a polymerization reactor in which monomers having polymerizable double bonds (including mixtures of the same monomers) are subjected to emulsion polymerization or fine suspension polymerization, the monomers are transferred to the polymerization reactor during the polymerization reaction. A polymerization apparatus characterized in that a supply pipe for supplying and/or auxiliaries is opened below the liquid surface of a liquid phase portion of a polymerization reaction system in the polymerization reactor. (5) A fourth pipe configured to open supply pipes for supplying monomers and/or auxiliary agents to the polymerization reactor during the polymerization reaction at multiple locations below the liquid surface of the liquid phase of the polymerization reaction system. A polymerization apparatus according to the claims. (6) The polymerization apparatus according to claim 4 or 5, wherein the monomer having a polymerized double bond is vinyl chloride or a monomer mixture containing vinyl chloride as a main component.