KR101831018B1 - Method for producing styrene-based hollow bead regardless of pH - Google Patents

Abstract

The present invention relates to a method for producing a styrene-based hollow bead. More specifically, the present invention relates to a method for producing a hollow bead regardless of the acidity of a water-based styrenic resin using suspension polymerization.

Description

[0001] The present invention relates to a method for producing styrene-based hollow beads independent of acidity,

The present invention is a method for producing a styrene-based hollow bead. More specifically, the present invention relates to a process for producing a hollow styrenic copolymer produced by suspension polymerization regardless of the acidity of the aqueous system, and a hollow styrenic copolymer produced by the process.

As a method of producing a hollow bead using suspension polymerization, it is necessary to allow the monomer droplet of the monomer to continuously carry out polymerization while trapping the air. Generally, when the air is filled in the monomer droplet, the surface energy of the droplet is changed to become unstable, so that the trapped air escapes out of the droplet due to collision between the droplets, or the shape of the monomer droplet is disturbed.

As a method for stabilizing the monomer droplets capturing the air, there is a method of appropriately stirring using an agitator or appropriately arranging the inner structure of the reactor to form a proper vortex so that air can flow well in the monomer droplet at the upper part of the reactant.

However, these methods are difficult to process, and it is difficult to produce a hollow bead having a uniform morphology through the above method.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a hollow styrenic copolymer having a homogeneous morphology regardless of the acidity of the aqueous system.

Another object of the present invention is to provide a hollow styrenic copolymer having improved self-dispersibility and self-healing function.

In order to achieve the above object, the present invention can provide a hollow styrenic copolymer having an empty hollow interior and a bulk density of 0.4 to 0.7 g / ml.

The hollow styrenic copolymer according to one embodiment of the present invention is prepared by copolymerizing from a mixture comprising (A) 40 to 80% by weight of an aromatic vinyl compound and (B) 20 to 60% by weight of an unsaturated nitrile compound .

In the hollow styrenic copolymer according to an embodiment of the present invention, the content of the organic dispersant may be 0.5% by weight or less.

 The present invention also relates to a process for producing a monomer mixture comprising an aromatic vinyl monomer, an unsaturated nitrile monomer and an initiator,

Preparing an aqueous dispersion medium containing an organic dispersion stabilizer; and

And discharging the monomer mixture liquid in the form of droplets into an aqueous dispersion medium, followed by suspension polymerization, to prepare a hollow styrene-based copolymer.

In the method for producing a hollow styrenic copolymer according to an embodiment of the present invention, the organic dispersant may be selected from the group consisting of polyacrylic acid, a poly (acrylic acid-alkyl acrylate) copolymer, polyvinyl alcohol, polyvinyl pyrrolidone, Ethyl cellulose, hydroxypropyl cellulose, and polyethylene oxide.

In the method for producing a hollow styrenic copolymer according to an embodiment of the present invention, the suspension polymerization may be carried out by stirring at 100 to 300 rpm (0.785 to 2.355 m / s).

In the process for producing a hollow styrenic copolymer according to an embodiment of the present invention, the suspension polymerization can be carried out at 70 to 100 ° C.

In the method of producing a hollow styrenic copolymer according to an embodiment of the present invention, the aqueous dispersion medium may further include at least one inorganic dispersant selected from monosodium phosphate, disodium phosphate, trisodium phosphate and sodium phosphate hydrate can do.

The thermoplastic resin composition containing the above-mentioned hollow styrene-based copolymer of the present invention can be provided.

The thermoplastic resin composition according to one embodiment of the present invention may include a styrene-acrylonitrile copolymer (SAN) resin composition, a methyl methacrylate-styrene-acrylonitrile copolymer (MSAN) resin composition, an acrylonitrile-butadiene- Styrene-acrylate copolymer (ASA) resin composition, polycarbonate (PC) / acrylonitrile-butadiene-styrene copolymer (MABS) resin composition, Acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition, polycarbonate (PC) / acrylonitrile-styrene-acrylate copolymer (ASA) (PMMA) / acrylonitrile-butadiene-styrene copolymer (ABS) alloy resin composition, polymethyl methacrylate (PMMA) / methyl methacrylate-acrylonitrile- (PMMA) / acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition and a mixture thereof, as well as a resin composition of a polybutylene terephthalate resin, a diene-styrene copolymer (MABS) alloy resin composition, a polymethylmethacrylate And may be at least one selected from the group consisting of

Further, the present invention can provide a molded article comprising the thermoplastic resin composition containing the styrenic copolymer.

The present invention has an advantage of being able to provide a method for producing a hollow styrene-based copolymer having a simple process and hollow interior with uniform morphology irrespective of the acidity of the aqueous system.

The hollow styrenic copolymer according to the present invention can be encapsulated and released and can be applied to various industrial fields such as medicine. It can be applied to microcracks There is an advantage that the self-healing function is given to the user.

1 and 2 are graphs showing the results obtained by measuring the powder obtained after dewatering and drying after polymerization according to the production method according to Example 1 and Comparative Example 1 of the present invention by staking the copolymer particles fixed to the respective epoxy resins, A SEM photograph is shown.

Hereinafter, the hollow styrenic copolymer of the present invention will be described in detail. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. It will be apparent to those skilled in the art that, unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, And a description of the known function and configuration will be omitted.

The inventors of the present invention have surprisingly found that, in order to stabilize a hydrophilic and a monomer / air (hydrophobic) in order to stabilize a monomer droplet capturing the air, the hydrophilicity and the hydrophobicity balance of the dispersing agent are optimally optimized, The present inventors have found that a hollow styrenic copolymer having a homogeneous morphology can be prepared without any problems.

The hollow styrenic copolymer according to the present invention has a hollow shape with an empty interior. It may have an air layer inside, and the outer layer surrounding the air layer may include a styrenic copolymer.

The hollow styrenic copolymer may have a bulk density of 0.4 to 0.7 g / ml, preferably 0.55 to 0.65 g / ml. The hollow styrenic copolymer has an advantage of being excellent in transporting and dispersing properties due to the reduction of the density in the process of manufacturing a thermoplastic resin composition described later and a molded article using the hollow styrenic copolymer and securing uniform physical properties without sedimentation.

The hollow styrenic copolymer according to one embodiment of the present invention may be one produced by suspension polymerization. The hollow styrenic copolymer may be prepared by including an organic dispersant for dispersion and suspension stability in suspension polymerization. The hollow styrenic copolymer obtained by the post-polymerization washing, dehydration and drying processes according to the use of the organic dispersant may contain 0.5% by weight or less of the organic dispersant.

Wherein the organic dispersant is at least one organic compound selected from the group consisting of polyacrylic acid, poly (acrylic acid-alkyl acrylate) copolymer, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, hydroxypropyl cellulose and polyethylene oxide . ≪ / RTI >

The styrenic copolymer according to an embodiment of the present invention may be prepared from a monomer mixture comprising an aromatic vinyl compound and an unsaturated nitrile compound.

In the present invention, the aromatic vinyl compound may be any one selected from the group consisting of styrene, vinyltoluene, t-butylstyrene, halogen-substituted styrene, 1,3-dimethylstyrene, 2,4-dimethylstyrene, Or more, and is not necessarily limited thereto. The aromatic vinyl compound is preferably styrene.

In the present invention, the aromatic vinyl compound may be contained in an amount of 40 to 80% by weight based on the total weight of the monomers used for preparing the hollow styrenic copolymer. Preferably 60 to 80% by weight. When the content of the aromatic vinyl compound is satisfied, excellent impact resistance and processability can be realized.

In the present invention, the unsaturated nitrile compound may be at least one selected from acrylonitrile, methacrylonitrile, ethacrylonitrile, phenyl acrylonitrile,? -Chloroacrylonitrile, and mixtures thereof. It is not limited. The unsaturated nitrile compound may preferably be acrylonitrile.

In the present invention, the unsaturated nitrile compound may be contained in an amount of 20 to 60% by weight based on the total weight of the monomers used for preparing the hollow styrenic copolymer. Preferably 20 to 40% by weight. When the content of the unsaturated nitrile compound is satisfied, the chemical resistance of the composition can be maintained without deteriorating other physical properties in combination with other components.

The present invention relates to a process for producing a monomer mixture comprising an aromatic vinyl monomer, an unsaturated nitrile monomer and an initiator,

Preparing an aqueous dispersion medium containing an organic dispersant, and

And discharging the monomer mixture liquid in the form of droplets into an aqueous dispersion medium, followed by suspension polymerization, to prepare a hollow styrene-based copolymer.

In the polymerization process of a monomer in the present invention, a radical is generated by an initiator, and the radical reacts with the polymerizable monomer to form a copolymer. Examples of the initiator include persulfates such as potassium persulfate and ammonium persulfate; 2-azobis (2-amidinopropane) dihydrochloride, 2, 3-azobis (2-aminopropanecarboxylic acid) Azobis-2-methyl-N-1,1-bis (hydroxymethyl) -2-hydroxyethylpropioamide, 2,2'-azobis (2,4-dimethylvaleronitrile), 2 , Azo compounds such as 2'-azobisisobutyronitrile and 1,1'-azobis (1-cyclohexanecarbonitrile); But are not limited to, methyl ethylperoxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, Oxydicarbonate, and di-t-butylperoxyisophthalate, and the like. Of these, azobisisobutyronitrile and benzoyl peroxide, which are hydrophobic polymerization initiators, are more preferable. An oxidation-reduction initiator in which these polymerization initiators and a reducing agent are combined can be mentioned.

Specifically, in the hollow styrenic copolymer according to an embodiment of the present invention, the monomer mixture liquid containing the monomer to be copolymerized and the initiator is discharged in a droplet form into an aqueous dispersion medium containing an organic dispersant. At this time, the aqueous dispersion medium containing the organic dispersant is stirred at 100 to 300 rpm (0.785 to 2.355 m / s) to form a vortex so that air can flow well, and at the same time, the suspension polymerization reactivity can be improved. The liquid droplets of the monomer mixture liquid capture air at the time of discharging, and the air trapped in the droplets of the monomer mixture liquid and the monomer mixture liquid becomes hydrophobic. It has a physical property balance with an aqueous dispersion medium containing an organic dispersant which is amphiphilic, and thus can produce a hollow styrene-based copolymer having a uniform morphology. An inorganic dispersant may be included in order to balance the hydrophobicity represented by the air trapped in the droplets of the monomer mixture liquid and the monomer mixture liquid and the hydrophilicity of the aqueous dispersion medium.

The aqueous dispersion medium is prepared by dissolving an organic dispersant in an appropriate amount in water. For example, an aqueous dispersion medium may be prepared by dissolving an organic dispersant in distilled water. Due to the inherent solid adsorption properties, the organic dispersant can control the size and distribution of the particles when forming the copolymer from the polymerizable monomers.

Wherein the organic dispersant is at least one organic compound selected from the group consisting of polyacrylic acid, poly (acrylic acid-alkyl acrylate) copolymer, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, hydroxypropyl cellulose and polyethylene oxide . ≪ / RTI >

At this time, the organic dispersant may be used in an amount of 0.5 part by weight or less based on 100 parts by weight of the total weight of the monomers to be copolymerized. Preferably 0.005 to 0.1 part by weight. When the content range of the organic dispersant is satisfied, a hollow styrenic copolymer having a homogeneous morphology can be produced, and the yield thereof can also be improved.

The aqueous dispersion medium may further comprise an inorganic dispersant at the same time as the organic dispersant. The inorganic dispersing agent may be selected from monosodium phosphate, disodium phosphate, trisodium phosphate and sodium phosphate hydrate, but not always limited thereto.

The suspension polymerization can be carried out at a temperature in the range of 70 to 100 占 폚, preferably 75 to 90 占 폚. Outside of the above range, the polymerization uniformity may be lowered, and thus the physical properties of the copolymer produced may be deteriorated.

In addition, the present invention may further comprise a molecular weight controlling agent for controlling the molecular weight when preparing the suspension. The molecular weight regulator may be selected from the group consisting of n-dodecyl mercaptan, n-amyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, And the content may be 0.01 to 0.5 parts by weight based on 100 parts by weight of the total amount of the monomers.

The present invention can provide a thermoplastic resin composition comprising the above-mentioned hollow styrenic copolymer produced by the above-described production method. The hollow styrenic copolymer is advantageous in that it can be mixed with other resins to realize high molding processability and impact resistance.

At this time, the thermoplastic resin composition may be a styrene-acrylonitrile copolymer (SAN) resin composition, a methyl methacrylate-styrene-acrylonitrile copolymer (MSAN) resin composition, an acrylonitrile-butadiene-styrene copolymer (PC) / acrylonitrile (ABS) resin composition, a methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS) resin composition, an acrylonitrile-styrene- -Butadiene-styrene copolymer (ABS) alloy resin composition, polycarbonate (PC) / acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition, polymethyl methacrylate (PMMA) / acrylonitrile-butadiene-styrene copolymer (ABS) alloy resin composition, polymethylmethacrylate (PMMA) / methyl methacrylate-acrylonitrile-butadiene-styrene (PMMA) / acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition, and mixtures thereof. , And is not necessarily limited thereto.

The thermoplastic resin composition may further include an additive depending on each application. For example, the thermoplastic resin composition may be selected from the group consisting of an impact modifier, a dripping inhibitor, an antioxidant, a plasticizer, a heat stabilizer, a light stabilizer, a compatibilizer, a weather stabilizer, a pigment, a dye, a colorant, And may further include at least one additive, but is not necessarily limited thereto.

The thermoplastic resin composition can be produced by a known method for producing a resin composition. For example, the components of the present invention and other additives may be simultaneously mixed and then melt-extruded in an extruder to produce pellets or chips.

Further, the present invention can provide a molded article comprising the thermoplastic resin composition. There is no particular limitation on the method of molding the molded article, and extrusion, injection, compression, cast molding or the like can be applied.

The present invention can provide a molded article comprising the thermoplastic resin composition containing the hollow styrenic copolymer. This is advantageous in that it can be applied in various industrial fields such as medicine because encapsulation and release are possible.

For example, the thermoplastic resin composition containing the styrenic copolymer can be applied to various industrial fields such as various electric and electronic products, automobile parts, and the like to provide a molded article.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.

The specifications of each component used in the following examples and comparative examples are as follows.

(evaluation)

(1) Yield

The content of the obtained copolymer was measured in comparison with the total weight of monomers charged at the time of production.

(2) Weight average molecular weight (Mw)

The powder sample was dissolved in THF, and the weight average molecular weight was measured at 35 캜 using Gel Permeation Chromatography (GPC; lient Technologies 1200 series). Shodex LF-804 (8.0.1.D. × 300 mm) was used as a column, and polystyrene (Shodex) was used as a standard sample.

(3) Glass transition temperature (Tg)

Using DSC Q20 from TA Instrument, the temperature was first raised to 160 deg. C at a rate of 20 deg. C / min, and then gradually cooled to maintain the equilibrium at 50 deg. C and then raised to 160 deg. C at a rate of 10 deg. The inflection point of the endothermic transition curve was determined as the glass transition temperature.

(Example 1)

(AIBN) was added to 1400 g of ion-exchanged water to prepare a monomer mixture composed of 75% by weight of styrene (SM) and 25% by weight of acrylonitrile (AN) and 100 parts by weight of the monomer mixture, 0.006 part by weight of poly (acrylic acid - (2-ethylhexyl acrylate)) copolymer (ETP), 0.65 part by weight of sodium phosphate (NAP) and 0.04 part by weight of polyethylene oxide (PEO) were used. Then 0.05 part by weight of n-dodecylmercaptan was added to the reactor as a molecular weight regulator and stirred at 300 rpm (2.355 m / s) to prepare a suspension. The suspension was placed in a reactor coated with a SUS material, heated to 80 DEG C, reacted at 300 rpm (2.355 m / s) for 2 hours, cooled, centrifuged and separated by solid-liquid separation Dehydrated and dried to obtain a hollow styrene-based copolymer.

(Example 2)

Except that 0.006 part by weight of ETP, 1.0 part by weight of NAP and 0.04 part by weight of polyethylene oxide were used as a dispersant in 100 parts by weight of the monomer mixture.

(Example 3)

Except that 0.01 part by weight of ETP, 0.65 part by weight of NAP and 0.04 part by weight of polyethylene oxide were used as a dispersant in 100 parts by weight of the monomer mixture.

(Examples 4 and 5)

The pH was adjusted to 10.5 and 5.5, respectively, in the same manner as in Example 1. Sodium hydroxide solution (1%) was set to set the pH of 10.5, and sulfuric acid solution (1%) was added to set the pH to 5.5.

 (Comparative Example 1)

The procedure of Example 1 was repeated except that ETP and NAP were not used as dispersants and 0.5 parts by weight of tricalcium phosphate (TCP) was added to 100 parts by weight of the monomer mixture.

As can be seen from Table 1, the hollow styrenic copolymers according to Examples 1 to 5 of the present invention were able to secure a yield of 80 wt% or more by including an organic dispersant and were not affected by the aqueous pH . On the other hand, in Comparative Example 1, the hollow styrenic copolymer yield was 5 wt%, indicating that the efficiency of producing a hollow copolymer was significantly lower than that of the example according to the present invention. 1 and 2, Example 1 according to the present invention forms a uniform morphology (FIG. 1), whereas Comparative Example 1 shows that precipitates are generated considerably and the yield is significantly lowered (Fig. 2).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Various modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (10)

(Acrylic acid-alkyl acrylate) copolymer (A) in the form of a droplet in the form of a mixture of a monomer mixture comprising (A) 40 to 80% by weight of an aromatic vinyl compound and 20 to 60% by weight of an unsaturated nitrile compound , A sodium phosphate and a polyethylene oxide dispersant and then suspended and polymerized. The hollow styrene-based styrene-based styrene-based styrene-based styrene-based styrene-based styrene- Copolymer.
delete A monomer mixture comprising an aromatic vinyl monomer, an unsaturated nitrile monomer and an initiator;
Preparing an aqueous dispersion medium comprising a poly (acrylic acid-alkyl acrylate) copolymer, a dispersant comprising sodium phosphate and polyethylene oxide; And
And discharging the monomer mixture solution into an aqueous dispersion medium in the form of droplets to perform suspension polymerization.
delete The method of claim 3,
Wherein the suspension polymerization is carried out with stirring at 0.785 to 2.355 m / s.
The method of claim 3,
Wherein the suspension polymerization is carried out at 70 to 100 占 폚.
delete A thermoplastic resin composition comprising the hollow styrenic copolymer of claim 1.
9. The method of claim 8,
The thermoplastic resin composition may be a styrene-acrylonitrile copolymer (SAN) resin composition, a methyl methacrylate-styrene-acrylonitrile copolymer (MSAN) resin composition, an acrylonitrile-butadiene-styrene copolymer Styrene-acrylate copolymer (ASA) resin composition, polycarbonate (PC) / acrylonitrile-butadiene-styrene copolymer (ABS) alloy resin composition, polycarbonate (PC) / acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition, polymethylmethacrylate (PMMA) / acryl Butadiene-styrene copolymer (ABS) alloy resin composition, polymethyl methacrylate (PMMA) / methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS) alloy resin composition, a resin composition selected from the group consisting of polymethylmethacrylate (PMMA) / acrylonitrile-styrene-acrylate copolymer (ASA) alloy resin composition and mixtures thereof At least one thermoplastic resin composition.
A molded article comprising the thermoplastic resin composition of claim 8.

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