JP5249512B2 - Method for producing polymer particles - Google Patents

Description

  The present invention provides, for example, an acrylic plastisol comprising an additive for paint, a plasticizer and the like, an acrylic organosol obtained by adding an organic solvent thereto, a modifier for a resin, a processing aid, a toner and the like, useful as a polymer particle. It relates to a manufacturing method.

In the presence of seed latex, a reaction liquid containing vinyl monomers is added sequentially and polymerized in combination with a surfactant, etc. as necessary, and the particle size is enlarged without changing the number of seed particles. This method is called seed emulsion polymerization.
When scaling up the reactor used for such a polymerization reaction, the reactor is designed to be geometrically similar, and the stirrer has a stirring motor power (torque) per unit volume of reactor content. In many cases, the design and conditions are set so as to be almost constant. Further, the time required for the concentration of the tracer or the like added to the reactor to become constant (mixing time) becomes longer as the scale of the reactor becomes larger.
As a result, in the seed emulsion polymerization method, the mixing time of the reaction liquid to be sequentially added increases as the reactor scales up, and the amount of aggregates generated may increase accordingly.

Therefore, the reaction liquid that is sequentially added during seed emulsion polymerization is an emulsion dispersion containing a vinyl monomer, water, and a surfactant, and in particular, aggregates are generated by reducing the size of the vinyl monomer droplets. A method of suppressing has been proposed (see, for example, Patent Documents 1 and 2).
In addition, a method has been proposed in which a reaction solution that is sequentially added at the time of seed emulsion polymerization is added into a reactor in the form of a shower or mist through a nozzle (see, for example, Patent Document 3). In Patent Document 3, as a method of adding the reaction liquid in a shower form, a method of adding the reaction liquid through a shower nozzle having a plurality of pores is cited. Further, as a method of adding the reaction liquid in the form of a mist, there is a method of adding the reaction liquid through a nozzle provided with an orifice mechanism or the like in the opening.
JP-T-2001-504544 Special table 2004-528450 gazette JP 2004-339413 A

However, the methods described in Patent Documents 1 and 2 have limitations on the rate of addition of the reaction solution to be sequentially added and the scale of the reactor in order to obtain the effect of suppressing the generation of aggregates.
Further, in the method described in Patent Document 3, the method of using a shower nozzle has no limitation on the discharge flow rate of the reaction solution, but has almost no effect of dispersing the reaction solution, so the scale of the reactor is increased. However, if the discharge flow rate is increased in order to increase the addition rate of the reaction liquid, it is difficult to obtain the effect of suppressing the generation of aggregates. In addition, the method using a nozzle having an orifice mechanism or the like in the opening has a certain effect of dispersing the reaction solution, but requires a high pressure, and thus has a limited discharge flow rate. As described above, when increasing the discharge flow rate or increasing the scale of the reactor for any nozzle, it is difficult to prevent an increase in the amount of aggregates generated. There was a limit to the scale of the reactor.

  The purpose of the present invention is to prevent an increase in the amount of agglomerates and stabilize the product with high productivity even when the reaction scale is larger or when the addition rate of the reaction solution added sequentially during seed emulsion polymerization is increased. It is to produce polymer particles.

  As a result of intensive investigations to achieve the above-mentioned problems, the inventors of the present invention have made it possible to disperse a reaction liquid that is sequentially added during seed emulsion polymerization through a dispersion nozzle in a wide range within the reactor, thereby adding a scale of the reactor. The present inventors have found that the amount of agglomerates generated can be suppressed regardless of the addition rate of the reaction solution and the reaction solution.

That is, the method for producing polymer particles of the present invention includes the step of adding a reaction liquid containing one or more vinyl monomers in the presence of seed latex to perform seed emulsion polymerization, and producing the polymer particles. When adding the liquid during seed emulsion polymerization, the reaction liquid is added to the reactor through a dispersion nozzle that applies a centrifugal force to the reaction liquid according to the liquid pressure, and the unit of the dispersion nozzle opening The discharge flow rate per area is 1000 to 20000 kg / (sec · m ² ).
Here, it is preferable to discharge from the dispersion nozzle with a discharge angle of 40 to 110 °.

  According to the present invention, it is possible to prevent an increase in the amount of agglomerates and improve productivity even in the case of a larger scale or in the case of increasing the rate of addition of a reaction solution sequentially added during seed emulsion polymerization. A method for producing a polymer particle can be provided.

Hereinafter, the present invention will be described in detail.
In the method for producing polymer particles of the present invention, when a reaction liquid containing at least one vinyl monomer (hereinafter referred to as “reaction liquid”) is added during seed emulsion polymerization, it is added into the reactor through a dispersion nozzle. Process.
The reaction solution is added in the presence of seed latex. The seed latex can be obtained by polymerizing a vinyl monomer in an aqueous medium in the presence of a polymerization initiator by an ordinary method such as emulsion polymerization or soap-free polymerization, and soap-free polymerization is particularly desirable. In addition, the mass average particle diameter of the seed particles in the seed latex obtained at this time is preferably about 0.2 to 1.0 μm. In this case, the effect of the present invention can be obtained more remarkably.

  Examples of the vinyl monomer used in the present invention include aromatic vinyl compounds such as styrene, α-methylstyrene, divinylbenzene; methyl methacrylate, methyl acrylate, t-butyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, Examples include (meth) acrylate compounds such as 2-ethylhexyl acrylate, n-butyl acrylate, and ethylene glycol dimethacrylate; and diene compounds such as butadiene. It is particularly useful and desirable when it is methyl methacrylate or n-butyl methacrylate.

As vinyl monomers, in addition to the above, carboxyl group-containing vinyl monomers such as methacrylic acid and acrylic acid or salts thereof; styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, sodium styrene sulfonate, etc. It is desirable to use a sulfonic acid group-containing vinyl monomer or a salt thereof; a hydroxyl group-containing vinyl monomer such as hydroxyethyl methacrylate, and the effects of the present invention can be obtained more remarkably.
A vinyl monomer may be used individually by 1 type according to the use of the polymer particle obtained, or may use 2 or more types together.

  Although it does not restrict | limit especially as a polymerization initiator used for this invention, It is desirable to use an anionic water-soluble radical polymerization initiator, and the inorganic salt of persulfuric acid etc. can be illustrated. Specific examples include thermal decomposition types such as potassium persulfate, ammonium persulfate, and sodium persulfate. Although these usage-amounts can be determined suitably, about 0.01-10 mass parts is preferable with respect to 100 mass parts of vinylic monomers.

In the present invention, if a reaction liquid is added and seed emulsion polymerization is performed in the presence of seed latex, a vinyl monomer is polymerized by soap-free polymerization or the like to produce a seed latex, and then the reaction liquid is added and seed emulsion polymerization is performed. Alternatively, after the seed latex is manufactured, a part or the whole amount of the seed latex may be used to separately add a reaction solution and perform seed emulsion polymerization.
In addition, what was mentioned above can be illustrated as a vinyl-type monomer contained in the said reaction liquid.

The reaction solution may be a vinyl monomer, a vinyl monomer emulsified with water and a surfactant, an aqueous vinyl monomer solution, or the like. Among them, it is preferable to mix the vinyl monomer, water, and the surfactant into an emulsified dispersion in advance.
Although it does not specifically limit as an emulsification method, The method of stirring strongly using a homomixer etc. can be illustrated. The amount of surfactant and water used for emulsification and the conditions for emulsification are generally determined by the amount of vinyl monomer and the amount necessary to maintain colloidal stability depending on the final polymer concentration. Although not determined, it is desirable that the vinyl monomer oil droplets in the reaction liquid (emulsified dispersion) have a size of 20 μm or less.

  As the surfactant, an anionic surfactant is preferably used. The anionic surfactant is not particularly limited as long as it has an anionic surfactant ability. For example, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dialkylsulfosuccinate, sodium alkyldiphenylether disulfonate , Sodium polyoxyethylene lauryl ether sulfate, potassium oleate, sodium stearate and the like. Of these, sodium alkyldiphenyl ether disulfonate, sodium dialkylsulfosuccinate, and sodium dodecylbenzenesulfonate are preferred, and these are suitable because they can effectively impart polymerization stability without changing the number of polymer particles. is there.

There is no limitation on the mass ratio of the vinyl monomer used during seed latex production and seed emulsion polymerization, but the amount of vinyl monomer used during seed latex production is 0 with respect to 100 parts by mass of the total amount of vinyl monomer used. It is desirable to set it as 5-30 mass parts.
The temperature during seed latex production and seed emulsion polymerization is preferably in the range of 65 to 95 ° C.

In the method for producing polymer particles of the present invention, the reaction liquid added at the time of seed emulsion polymerization is added into the polymerization reactor through a dispersion nozzle.
The dispersion nozzle used in the present invention has swirl vanes and the like inside the nozzle, and can apply a centrifugal force according to the fluid pressure to the reaction solution. Thereby, since the reaction liquid discharged from the nozzle is added to the reactor while spreading over a wide range, an increase in the amount of aggregates generated can be suppressed. Moreover, since the dispersion nozzle does not require high pressure, the discharge flow rate can be set in a wide range.
The spreading method of the reaction liquid discharged from the nozzle is determined by the centrifugal force, that is, the hydraulic pressure (flow velocity), the angle of the swirl blade, the cross-sectional area of the nozzle opening, and the like. Can be set large.

Examples of such a dispersion nozzle include a one-fluid spray nozzle manufactured by Spraying Systems Japan Co., Ltd.
If a shower type nozzle having a plurality of pores or a mist type nozzle provided with an orifice mechanism or the like is used instead of the dispersion nozzle, the discharge flow rate is limited as described above. It is difficult to increase the addition rate of the polymerization reactor and the scale of the polymerization reactor.

Although the discharge pattern of a dispersion | distribution nozzle is not restrict | limited in particular, A full cone, a holo cone, and a flat type can be illustrated. In particular, a full cone type discharge pattern is preferable because the effect of the present invention is more noticeable.
The reaction liquid discharged from the dispersion nozzle is desirably added uniformly to the liquid surface in the polymerization reactor. Specifically, it is desirable that the reaction liquid to be added is always uniformly added in a range of 30 to 100% with respect to the final area of the liquid surface in the polymerization reactor.

  The mounting position and mounting angle of the dispersion nozzle are appropriately determined in consideration of the discharge angle of the dispersion nozzle, the final liquid level of the reactor, etc., but the final liquid level of the polymerization reactor is It is desirable to prevent the reaction solution from hitting a position higher than that (the inner wall surface of the reactor).

Discharge flow rate per unit area of the dispersion nozzle opening is ^{1000~20000kg / (sec · m 2)} , 2000~20000kg / (sec · m 2) is ^{preferred, 3000~20000kg / (sec · m 2} ) is More preferred. By setting the discharge flow rate within the above range, an effect of suppressing the amount of aggregates generated can be obtained.

  The discharge angle of the dispersion nozzle is preferably 40 ° to 110 °. The discharge angle is an angle α shown in FIGS. 1 and 2 and is an angle formed when the reaction liquid is discharged from the dispersion nozzle in a spray form by centrifugal force. A more preferable discharge angle is 65 ° to 110 °. By setting the discharge angle within the above range, the reaction solution can be discharged uniformly and over a wide range.

In the present invention, a more remarkable effect is obtained when the internal volume of the polymerization reactor is 1 m ³ or more. When the internal volume is 10 m ³ or more, particularly when the internal volume is 30 m ³ or more, a more remarkable effect can be obtained.

  In this way, since the dispersion nozzle does not require high pressure, the discharge flow rate can be set in a wide range, so that the discharge flow rate can be changed according to the scale-up of the polymerization reactor. Moreover, since the reaction liquid discharged from the dispersion nozzle is added to the reactor while spreading over a wide range, an increase in the amount of aggregates generated can be suppressed.

As described above in detail, according to the method for producing polymer particles of the present invention, seed emulsion polymerization can be performed without increasing the amount of aggregates, particularly on an industrial scale, and therefore polymer particles can be produced with high productivity. .
Therefore, the industrial significance brought about by the present invention is remarkable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

[Polymerization reactor]
As shown in FIG. 1, a stirring tank 11 was used as the polymerization reactor 10. The stirring tank 11 includes a dispersion nozzle 12, a stirring shaft 13, a stirring blade 14 including an upper blade 14a and a lower blade 14b, and two plate baffles 15. The stirring blade 14 uses a Max blend blade and has an arm 16, an inner strip 17, and an outer strip 18. Further, the lower blade 14 b includes a flat paddle 19 at the lower part. The material of the stirring blade 14 and the inner wall surface of the reactor 11 is SUS304, the ratio between the upper blade diameter d1 and the tank diameter D is d1 / D = 0.55, and the ratio between the lower blade diameter d2 and the tank diameter D is d2 / D. = 0.60.

[Mass average particle diameter]
The mass average particle diameter of the polymer particles was measured using a laser diffraction / scattering particle size distribution analyzer (LA-910, manufactured by Horiba, Ltd.).

[Solid content]
The solid content of the latex was determined by drying the latex with a hot air dryer at 180 ° C. and measuring the mass of the latex before and after drying.

[Example 1]
1, 8541 kg of pure water was put into the polymerization reactor 10 shown in FIG. 1, and nitrogen gas was sufficiently passed through for 30 minutes to replace dissolved oxygen in the pure water. After stopping the aeration of nitrogen gas, 642 kg of n-butyl methacrylate was added, and the temperature was raised to 80 ° C. while stirring at 17 rpm. After the internal temperature reached 80 ° C., 6 kg of potassium persulfate dissolved in 280 kg of pure water was added into the polymerization reactor 10 to start soap-free polymerization (production of seed latex).
After 60 minutes from the start of polymerization, 12275 kg of n-butyl methacrylate, 325 kg of methacrylic acid, 100 kg of sodium dialkylsulfosuccinate (trade name: Perex O-TP) and 7161 kg of pure water were mixed and stirred to obtain an emulsified dispersion. This was added to the polymerization reactor 10 through the dispersion nozzle 12 over 200 minutes to perform seed emulsion polymerization. As the dispersion nozzle 12, a one-fluid nozzle (manufactured by Spraying Systems Japan Ltd., trade name: Distribojet Nozzle R) having an opening diameter of 20 mm was used. The discharge flow rate per unit area of the opening was 5270 kg / (sec · m ² ), the discharge angle of the dispersion nozzle 12 was 95 °, and the discharge pattern was a full cone type. Then, it kept at 80 degreeC for 1 hour, and cooled, and latex was obtained.
The solid content of the obtained latex was 45.1 wt%, and the particle size of the polymer particles was 765 nm.
The latex after the reaction is completed is filtered using a 150 mesh nylon mesh, and the obtained wet powder (aggregate) is dried in a hot air dryer at 50 ° C. for 24 hours, and then the mass is measured to determine the rate of occurrence of aggregates. (Wt%) was determined by the following equation. The results are shown in Table 1.
Aggregate generation rate (wt%) = (mass of aggregate) / (mass of all monomers) × 100

<Example 2>
A latex was produced in the same manner as in Example 1 except that the dispersion nozzle 12 having a discharge angle of 45 ° was used.
The obtained latex had a solid content of 45.0 wt%, and the particle size of the polymer particles was 780 nm. Table 1 shows the amount of aggregate generated after the completion of the reaction.

<Comparative Example 1>
A latex was produced in the same manner as in Example 1 except that the raw material for seed emulsion polymerization was added into the polymerization reactor through a SUS pipe (straight pipe) having an inner diameter of 20 mm without using a dispersion nozzle. The discharge angle of the pipe was approximately 0 °, and the discharge flow rate per unit area based on the pipe inner diameter was 5270 kg / (sec · m ² ).
The solid content of the obtained latex was 44.2 wt%, and the particle size of the polymer particles was 770 nm. Table 1 shows the amount of aggregate generated after the completion of the reaction.

<Comparative example 2>
Using a 1-fluid nozzle (trade name: Distribojet Nozzle R, manufactured by Spraying Systems Japan Co., Ltd.) with an opening diameter of the dispersion nozzle 12 of 70 mm, the discharge flow rate per unit area is set to the values shown in Table 1. A latex was produced in the same manner as in Example 1 except that.
The solid content of the latex obtained in Comparative Example 2 was 43.8 wt%, and the particle size of the polymer particles was 766 nm. Table 1 shows the amount of aggregate generated after the completion of the reaction.

<Comparative Example 3>
Using a 1-fluid nozzle (trade name: Distribojet Nozzle R, manufactured by Spraying Systems Japan Co., Ltd.) with an opening diameter of the dispersion nozzle 12 of 8 mm, the discharge flow rate per unit area is as shown in Table 1. A latex was produced in the same manner as in Example 1 except that. Since the flow rate of the emulsified dispersion passing through the dispersion nozzle did not reach the desired flow rate during the addition, it was pumped using a pump.
After completion of the reaction, the dispersion nozzle was disassembled and the inside of the opening was confirmed. As a result, solid matter was adhered and the opening was about to close.
The solid content of the latex obtained in Comparative Example 3 was 45.0 wt%, and the particle size of the polymer particles was 772 nm. Table 1 shows the amount of aggregate generated after the completion of the reaction.

As is clear from Table 1, the agglomerates contained in the latexes obtained by the examples were few.
On the other hand, the latex obtained in the comparative example contained a lot of aggregates.

It is a schematic sectional drawing which shows the polymerization reactor used in the Example. It is the figure which expanded the installation part of the dispersion nozzle with which the polymerization reactor shown in FIG. 1 is equipped.

Explanation of symbols

  10: polymerization reactor, 11: stirring tank, 12: dispersion nozzle, 13: stirring shaft, 14: stirring blade, 14a: upper blade, 14b: lower blade, 15: plate baffle, 16: arm, 17: inner strip, 18: Outer strip, 19: Flat paddle.

Claims (2)

In the method of producing polymer particles by adding a reaction liquid containing one or more vinyl monomers in the presence of seed latex and performing seed emulsion polymerization,
When adding the reaction liquid during seed emulsion polymerization, the reaction liquid is added into the reactor through a dispersion nozzle that applies centrifugal force to the reaction liquid according to the liquid pressure, and the dispersion nozzle opening The method according to claim 1, wherein the discharge flow rate per unit area is 1000 to 20000 kg / (sec · m ² ).   The method for producing polymer particles according to claim 1, wherein discharge is performed from the dispersion nozzle at a discharge angle of 40 to 110 °.

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