JP2003335803A - Process for producing bead polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing a bead polymer suitable for a raw material for paint, a raw material for ink, a dental material, a binder for a toner in a copying machine, a binder for ceramic calcination, an intermediate raw material for a thermoplastic resin or the like stably even in the case of the use of a large-size apparatus for suspension polymerization. <P>SOLUTION: The process for producing the bead polymer comprises setting a tip speed of a stirring blade to the range of 1-5 m/sec upon the initiation of the suspension polymerization of a vinyl-based monomer and changing the tip speed of the stirring blade in the course of the polymerization, wherein the tip speed of the stirring blade is changed when the polymerization degree of the vinyl-based monomer is in the range of 30-60 mass% and the tip speed of the stirring blade is changed to 1.2-5 times its initial speed in the course of the polymerization. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for stably producing a beaded polymer.

[0002]

2. Description of the Related Art The suspension polymerization method is a production technique which is particularly useful as a method for polymerizing vinyl-based monomers. Coalescence can be produced. This bead-shaped polymer is used for coating materials, ink materials, dental materials, binders for copier toners, binders for firing ceramics, intermediate materials for thermoplastic resins, and the like.

This bead-like polymer is produced after the polymerization step and further through steps such as dehydration, washing and drying of the slurry. The type of equipment used in each of these steps and the operating conditions depend on the quality of the product. , The production cost, energy consumption, amount of waste, etc. may be greatly affected. That is, the optimization of each process is an important production technology issue.

On the other hand, the demand for bead-like polymers is increasing with the expansion of their applications, and in order to respond to this, various studies have been made to increase the size of the apparatus in each step of producing the bead-like polymers. There is.

[0005]

However, in suspension polymerization, the heat of polymerization increases as the scale increases,
Along with this, it becomes difficult to sufficiently remove heat, which may make it difficult to control the polymerization. That is, there is a problem that the polymerization stability decreases when the suspension polymerization apparatus is enlarged.

An object of the present invention is to provide a method capable of stably producing a beaded polymer even when a large-sized suspension polymerization apparatus is used.

[0007]

As a result of intensive studies, the present inventors have found that the aforesaid problems can be solved by optimizing the stirring conditions during suspension polymerization, and completed the present invention.

That is, according to the present invention, the bead-shaped weight is set so that the tip speed of the stirring blade during the suspension polymerization of the vinyl monomer is in the range of 1 to 5 m / sec and the tip speed of the stirring blade is changed during the polymerization. The present invention relates to a method for manufacturing a united body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The vinyl-based monomer which is a constituent of the beaded polymer obtained by the present invention is not particularly limited, but unsaturated fatty acid ester, aromatic vinyl compound, vinyl cyanide Examples thereof include compounds, unsaturated dibasic acids or their derivatives, unsaturated fatty acids or their derivatives, and the like.

The unsaturated fatty acid ester is (meth)
Acrylic acid esters and the like can be used. The (meth) acryl of the present invention means methacryl or acryl. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, (meth)
Ethyl acrylate, n-propyl (meth) acrylate,
I-Propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, (meth)
(Meth) acrylic acid alkyl esters such as t-butyl acrylate and 2-ethylhexyl (meth) acrylic acid,
Cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, cycloalkyl esters of (meth) acrylic acid such as adamantyl (meth) acrylate, (meth) acrylic Acid phenyl, aromatic (meth) acrylic acid esters such as benzyl (meth) acrylate, fluorophenyl (meth) acrylate, chlorophenyl (meth) acrylate, fluorobenzyl (meth) acrylate, chlorobenzyl (meth) acrylate (Meth) acrylic acid substituted aromatic ester such as, (meth) acrylic acid fluoromethyl, (meth) acrylic acid halogenated alkyl ester such as fluoroethyl,
Examples thereof include (meth) acrylic acid hydroxyalkyl ester, (meth) acrylic acid glycidyl, (meth) acrylic acid ethylene glycol ester, and (meth) acrylic acid polyethylene glycol ester.

Examples of the aromatic vinyl compound include α-substituted styrenes such as styrene, α-methylstyrene and α-ethylstyrene, and nucleus-substituted styrenes such as fluorostyrene and methylstyrene.

Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

As the unsaturated dibasic acid or its derivative,
Examples thereof include N-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-chlorophenylmaleimide, maleic acid, maleic anhydride, and fumaric acid. be able to.

Examples of unsaturated fatty acids or derivatives thereof include (meth) acrylamides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, and (meth) acryl. Calcium acid, barium (meth) acrylate, lead (meth) acrylate, tin (meth) acrylate, (meth)
Examples thereof include metal salts of (meth) acrylic acid such as zinc acrylate and (meth) acrylic acid.

One or more of these vinyl-based monomers can be appropriately selected and used as a constituent of the beaded polymer. Among them, methyl (meth) acrylate,
Ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate,
It is preferable to use at least one selected from t-butyl (meth) acrylate. Further, it is particularly preferable to use 50% by mass or more of methyl methacrylate as a constituent component of the beaded polymer.

The beaded polymer of the present invention, which is produced by suspension polymerization of the above-mentioned vinyl monomer, usually has a shape close to a true sphere. The particle diameter of this bead-shaped polymer has a distribution, but the weight average particle diameter is usually within the range of 10 to 1000 μm.

The suspension polymerization is carried out by using the above-mentioned vinyl monomer, water,
Further, it can be carried out in a container having a polymerization temperature control function, a stirring function, etc., by using a polymerization initiator, a chain transfer agent, a dispersion stabilizer, a dispersion stabilization auxiliary agent or the like selected appropriately. Further, depending on the purpose, various additives such as an antioxidant and a release agent may be added during suspension polymerization.

The polymerization initiator usable in the present invention includes
For example, 2,2'-azobisisobutyronitrile, 2,
Azo initiators such as 2'-azobis-2,4-dimethylvaleronitrile, benzoyl peroxide, t-butylperoxy 2-ethylhexanoate, 1,1-di-t
Examples thereof include peroxide initiators such as -butylperoxy-2-methylcyclohexane. The amount of the polymerization initiator used is preferably in the range of 0.001 to 3 parts by mass with respect to 100 parts by mass of the vinyl monomer.

The chain transfer agent usable in the present invention includes:
For example, t-butyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, t-dodecyl mercaptan, etc. can be mentioned. The amount of the chain transfer agent used is 0 to 3 with respect to 100 parts by mass of the vinyl-based monomer.
It is preferably in the range of parts by mass.

The dispersion stabilizer that can be used in the present invention includes
For example, calcium phosphate, calcium carbonate, aluminum hydroxide, inorganic compounds such as starch powder silica, polyvinyl alcohol, polyethylene oxide, nonionic polymer compounds such as cellulose derivatives, polyacrylic acid and its salts, polymethacrylic acid and its salts, Examples thereof include anionic polymer compounds such as copolymers of methacrylic acid ester with methacrylic acid and its salts. One or more of these dispersion stabilizers can be appropriately selected and used as needed, but an anionic polymer compound is preferable. Among them, a copolymer of methacrylic acid ester with methacrylic acid and its salt is particularly preferable.

The amount of the dispersion stabilizer used is preferably 0.0005 to 1.5 parts by mass with respect to 100 parts by mass of the vinyl monomer. This is because when the amount of the dispersion stabilizer used is 0.0005 parts by mass or more, the stability of suspension polymerization tends to be improved, and when it is 1.5 parts by mass or less, the yield of the polymer is increased. Is improved, and the waste liquid after suspension polymerization tends to be easily treated.

As the dispersion stabilizing aid that can be used in the present invention, an electrolyte having a monovalent to trivalent cation can be used. For example, lithium, sodium, potassium, magnesium, calcium, manganese, zinc, copper,
Examples thereof include metal hydrochlorides such as nickel, iron and aluminum, sulfates, phosphates, borates, lower carboxylates having 1 to 4 carbon atoms, aliphatic sulfonates and aromatic sulfonates. it can. If necessary, one or more of these dispersion stabilizing aids can be appropriately selected and used, but sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, manganese sulfate, etc. are preferred. Of these, manganese sulfate is particularly preferable.

The amount of the dispersion stabilizing aid used is preferably 0.0005 to 3 parts by mass with respect to 100 parts by mass of the vinyl monomer.

In the present invention, the above vinyl-based monomer is added to an agitated aqueous medium in which the above-mentioned dispersion stabilizer, dispersion stabilizing aid, etc. are dissolved, and suspension polymerization is carried out at a predetermined polymerization temperature. By carrying out, a beaded polymer is produced. Suspension polymerization can be carried out in an inert atmosphere of nitrogen or the like, if necessary.

The amount of water used in the suspension polymerization is 100 to 500 with respect to 100 parts by mass of the vinyl monomer.
It is preferably in the range of parts by mass. More preferably 1
It is in the range of 50 to 300 parts by mass.

The polymerization temperature of suspension polymerization is 50 to 15
It is preferably in the range of 0 ° C. More preferably 50
It is in the range of to 130 ° C.

In the present invention, the container (polymerization tank) used for suspension polymerization has an inner diameter of 1.5 to 3 m and a height of 2 to 4 m.
It is preferably in the range of m. This is because when the inner diameter of the polymerization tank is 1.5 m or more and the height of the polymerization tank is 2 m or more, the productivity of the bead-shaped polymer tends to be excellent. Further, when the inner diameter of the polymerization tank is 3 m or less and the height of the polymerization tank is 4 m or less, the suspension can be sufficiently stirred and the heat of polymerization tends to be sufficiently removed.

The polymerization apparatus used for suspension polymerization is
Polymerization tank, a stirrer, those having a temperature control device can be appropriately selected and used, for example, a polymerization device in which the center of the stirring blade is at the center of the inner diameter of the polymerization tank, a polymerization device having a baffle plate in the polymerization tank, Examples include an eccentric stirring type polymerization device in which the center of the stirring blade is different from the center of the inner diameter of the polymerization tank, but among them, the center of the stirring blade is at the center of the inner diameter of the polymerization tank and a polymerization apparatus having a baffle plate in the polymerization tank. However, it is difficult to obtain a modified bead-shaped polymer enclosing bubbles, and a spherical bead-shaped polymer tends to be efficiently obtained, which is preferable.

The baffle which can be installed in the polymerization tank is not particularly limited, but the width is 5 to 1 of the inner diameter of the polymerization tank.
If the length is 5% or more and the length is 70% or more of the height of the polymerization tank, the downward vortex flow (vortex) formed near the stirring shaft is suppressed, and it is difficult to obtain a deformed bead-shaped polymer enclosing bubbles. It is preferable in that The number of baffles installed in the polymerization tank is not particularly limited, but it is 2 from the viewpoint of the effect of suppressing the downward vortex flow (vortex) formed near the stirring shaft.
-6 sheets are preferable, and 2 sheets are particularly preferable.

The stirrer which can be used in the present invention is not particularly limited, and may be a propeller type, screw type,
A paddle type, anchor type, etc. equipped with a stirring blade can be appropriately selected and used.

The size of the stirring blade is not particularly limited, but the stirring blade length is preferably in the range of 20 to 35% of the inner diameter of the polymerization tank, and the stirring blade width is 5 times the height of the polymerization tank. ~ 1
It is preferably in the range of 5%. This is because by setting the length of the stirring blade to 20% or more of the inner diameter of the polymerization tank, the tip speed of the stirring blade can be sufficiently obtained, and the stirring of the suspension tends to be sufficient. This is because the load on the stirrer tends to be reduced. Further, by setting the stirring blade width to 5% or more of the height of the polymerization tank, the stirring of the suspension tends to be sufficient, and by setting it to 15% or less, the load on the stirrer is reduced and This is because the life tends to be long.

The number of stirring blades is not particularly limited, but is preferably 2 to 8 and particularly preferably 4. The stirring blade may be provided in multiple stages. In addition, the angle of the stirring blade is such that the angle between the shear plane of the stirring blade and the stirring shaft is -45 to 4
It is preferably in the range of 5 °.

In the present invention, it is necessary to set the tip speed of the stirring blade within the range of 1 to 5 m / sec during the suspension polymerization of the vinyl monomer. This is because the mixing speed of the suspension tends to be insufficient when the stirring blade tip speed is less than 1 m / sec. It is preferably 2 m / sec or more. Also, if the tip speed of the stirring blade exceeds 5 m / sec, the amount of emulsion produced increases, and it tends to be difficult to produce a bead-shaped polymer having a narrow molecular weight distribution. Preferably 4
m / sec or less.

Further, in the present invention, it is necessary to change the tip speed of the stirring blade during the suspension polymerization of the vinyl monomer. This is because the production stability of the beaded polymer tends to be improved by changing the tip speed of the stirring blade during the polymerization.

The timing of changing the tip speed of the stirring blade is not particularly limited, but the polymerization rate of the vinyl monomer is 3
It is preferably carried out when it is in the range of 0 to 60% by mass. This is because when the polymerization is carried out at a polymerization rate of 30% by mass or more, the production of an emulsion is reduced, and a bead-shaped polymer having a narrow molecular weight distribution tends to be easily produced. More preferably, it is 40 mass% or more. Also,
This is because when the polymerization rate is 60% by mass or less, it is possible to sufficiently remove the heat generated by the polymerization and further improve the polymerization stability. More preferably, it is 50 mass% or less.

In the present invention, it is preferable to change the tip speed of the stirring blade to 1.2 to 5 times during the polymerization. This is because by changing the tip speed of the stirring blade to 1.2 times or more, it is possible to sufficiently remove the heat generated by the polymerization and to further improve the polymerization stability. More preferably, it is 1.5 times or more. Also, by changing the stirring blade tip speed to 5 times or less, the production of emulsion is reduced, and it tends to be easier to produce a bead-shaped polymer having a narrow molecular weight distribution. More preferably, it is 3 times or less.

The beaded polymer can be separated from the aqueous medium by filtering the slurry of the beaded polymer obtained by the present invention. The separated bead-like polymer can be further washed and dried. The bead-shaped polymer which has been subjected to the drying treatment can be taken out with a desired particle size by sieving.

The bead-like polymer obtained in the present invention can be used for coating materials, ink materials, dental materials, binders for copying machine toners, binders for firing ceramics, intermediate materials for thermoplastic resins and the like.

The beaded polymer obtained in the present invention can be pelletized through a shaping process such as injection molding, and the pellets can be used for molding materials. At the time of pelletizing, for example, colorants such as dyes and pigments, antioxidants, plasticizers, light stabilizers such as ultraviolet absorbers, and the like can be added as additives, if necessary.

[0040]

EXAMPLES The present invention and its effects are specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. The physical properties of the beaded polymers obtained in Examples and Comparative Examples were evaluated according to the following methods [1] to [3].

[1] Polymerization rate 1 ml of a suspension sampled during suspension polymerization was dissolved in 50 ml of acetone to obtain a HEWLETT PACKARD.
It was calculated from the amount of residual monomer measured by HP-6890 + type gas chromatograph manufactured by the same company.

[2] Polymerization time The time from the temperature rise of the contents of the polymerization vessel to the maximum temperature of the polymerization peak heat generation was measured with a stopwatch.

[3] Shape of bead-shaped polymer The shape of the bead-shaped polymer and the presence or absence of aggregation were visually confirmed.

(Production Example 1) A polymerization apparatus equipped with a stirrer was used.
A mixture of 100 parts by mass of an aqueous solution of potassium methacrylate (potassium methacrylate 30% by mass) and 70 parts by mass of methyl methacrylate was added, and the contents of the polymerization tank were heated while stirring. When the temperature of the contents of the polymerization tank reaches 72 ° C,
Ammonium persulfate 0.11 in 1.0 part by weight of deionized water
Put a polymerization initiator aqueous solution in which parts by mass are dissolved into a polymerization tank,
The temperature of the contents of the polymerization tank was maintained at 80 ° C for a certain period of time. Four hours after the peak of the heat of polymerization, 320 parts by mass of deionized water was charged into the polymerization tank, and at the same time, the contents of the polymerization tank were cooled to drain the anionic polymer compound aqueous solution (1) from the polymerization tank. Then, in order to collect the anionic polymer compound aqueous solution adhering to the wall surface of the polymerization tank, 480 parts by mass of deionized water was added to the polymerization tank and stirred, and then the temperature of the contents of the polymerization tank was kept at 60 ° C. for 1 hour. Then, the contents of the polymerization tank are cooled to collect the anionic polymer compound aqueous solution (2), and then the anion polymer compound aqueous solution (1) previously collected.
The mixture was mixed with and stirred to obtain an anionic polymer compound aqueous solution (3).

(Example 1) In a container equipped with a stirrer, 3600 kg of methyl methacrylate and 400 of methyl acrylate were used.
Then, 56 kg of benzoyl peroxide (75% by mass of pure content) was added as a polymerization initiator, and 40 kg of cetanol was added as a release agent, and the mixture was stirred and dissolved. Further, 8000 kg of deionized water was placed in a container equipped with another stirrer, 504 kg of the anionic polymer compound aqueous solution (3) obtained in (Production Example 1) as a dispersion stabilizer, and 0.2 kg of manganese sulfate as a dispersion stabilizing aid. , Hydrogen peroxide water (hydrogen peroxide content 35%)
2.8 kg was added and dissolved by stirring. Each mixed solution,
A polymerization tank having an inner diameter of 2500 mm and a height of 3200 mm, the center of the stirring blade is at the center of the polymerization tank inner diameter, and the stirring blade diameter is 150.
0 mm (stirring blade length = 600 mm), stirring blade width 200 m
It was put into a polymerization device equipped with a stirrer having a 2-stage paddle blade of m, a width of 180 mm, and a baffle plate of 2500 mm in length, and the stirring blade tip speed was 2.8 m / sec.
Polymerization was started at 0 ° C., and 100 minutes after the temperature was raised, the stirring blade tip speed was changed to 3.8 m / sec. The polymerization rate at this time was 35 mass%. Then, the exothermic peak of polymerization was confirmed, and cooling was performed to complete the polymerization, to produce a beaded polymer.
The maximum temperature reached for the polymerization peak exotherm is 88 ° C, and the polymerization time is 1
It was 40 minutes, the shape of the bead-shaped polymer produced was uniform and spherical, and the polymerization stability was good.

(Example 2) A bead-shaped polymer was produced under the same conditions as in Example 1 except that the polymerization rate was changed to 55% by mass when the stirring blade tip speed was changed. The maximum temperature at which the heat of polymerization peak reached was 90 ° C., the polymerization time was 137 minutes, the shape of the bead-shaped polymer produced was uniform and spherical, and the polymerization stability was good.

Example 3 A bead-like polymer was produced under the same conditions as in Example 1 except that the tip speed of the stirring blade after the change was 5.2 m / sec. The maximum temperature at which the heat generated in the polymerization peak reached was 87 ° C., the polymerization time was 142 minutes, the shape of the bead-shaped polymer produced was uniform and spherical, and the polymerization stability was good.

Comparative Example 1 A bead-like polymer was produced under the same conditions as in Example 1 except that the stirring blade tip speed was kept constant. The highest temperature at which the polymerization peak exotherm reached was 97 ° C., and the polymerization time was 131 minutes. As a result of increased heat generation during polymerization,
Polymerization stability was lowered, and a part of the obtained bead-like polymer was aggregated, and the quality was lowered.

[0049]

Industrial Applicability According to the present invention, heat removal during suspension polymerization is facilitated, and a bead-like polymer can be stably produced even when a large-sized suspension polymerization apparatus is used. It is very useful.

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Claims (3)

[Claims] 1. A method for producing a beaded polymer, wherein a tip speed of a stirring blade during suspension polymerization of a vinyl-based monomer is set in a range of 1 to 5 m / sec, and a tip speed of the stirring blade is changed during the polymerization. . 2. The method of producing a beaded polymer according to claim 1, wherein the stirring blade tip speed is changed when the polymerization rate of the vinyl monomer is in the range of 30 to 60 mass%. 3. A stirring blade tip speed of 1.2 to 5 during the polymerization.
The method for producing a beaded polymer according to claim 1 or 2, wherein the doubling is changed.