KR101400323B1 - Polymer beads having core-shell structure and Preparation method of polymer beads by core-shell method - Google Patents

Abstract

The present invention relates to a polymer bead having a core-shell structure and a method for producing the same, and more particularly, to a polymer bead having a core-shell structure comprising a core layer composed of polystyrene beads and a polyalkyl silsesquioxane shell layer . The present invention also relates to a process for producing polystyrene beads, which comprises the first step of preparing polystyrene beads as a core layer by suspension polymerization, and the first step of adding polystyrene beads by adding dropwise a solution containing an ion exchange water, an acid catalyst, an alkyltrialkoxysilane, A method for producing a polymer bead of a core-shell structure having a particle size of 1 to 20 mu m and a very uniform particle distribution with a coefficient of variation (CV) of less than 20%, including a second step of producing a sesquioxane shell layer .

Core-shell beads, polymer beads, polystyrene beads, polyalkyl silsesquioxanes

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer beads having a core-shell structure and a polymer beads having a core-

The present invention relates to a polymer bead having a core-shell structure and a method for producing the polymer bead. More particularly, the present invention relates to a polymer bead comprising a core layer and a polyisocyanurate as a shell layer, The present invention relates to a polymer bead having a very good core-shell structure and a method for producing the same.

The polymer particles are collectively referred to as spherical particles having a uniform particle size distribution prepared by emulsion polymerization or suspension polymerization. The polymer particles have a wide variety of uses, and are widely used not only for a light diffusion film, a protective film, and a construction for a liquid crystal monitor but also for a transparent film for a color ink. In addition, it is used for various applications such as toner, cosmetics, liquid crystal display spacer, anisotropic conductive film and conductive particles of anisotropic conductive adhesive. These polymer particles are technologically intensive, low in device dependency, and are relatively high-priced and high-value-added products in a relatively small quantity, unlike general-purpose polymers with high device dependence and low added value, such as olefin-based petrochemical products or nylon and polyester.

Among polystyrene beads, polystyrene beads have a refractive index of 1.59, which has a high refractive index and thus has an increased brightness and is being used as a diffusion agent for a light diffusion plate or a light diffusion film because of its low cost.

Such polystyrene beads are generally produced by methods such as suspension polymerization, dispersion polymerization and emulsion polymerization.

In suspension polymerization, the polymer particles are prepared by dispersing monomers present in the aqueous phase by mechanical force. The polymer particles produced by this method have a particle size of at least 100 mu m or more, and the particle distribution tends to be wide because the particles are dispersed by mechanical force. Therefore, a separate device is needed to control the particle size and particle distribution. In this connection, U.S. Patent Nos. 4,017,670, 4,071,670, 4,085,169 and 4,129,706 disclose techniques for producing polystyrene polymer beads by suspension polymerization.

The dispersion polymerization is carried out in a medium in which the monomer to be polymerized can be dissolved, and the resulting polymer is not dissolved in the medium. In addition, since this method has a high coagulation rate, the degree of crosslinking of the polymer beads produced is less than 2%, and the particle size distribution of polymer beads having a particle size of 10 탆 or more is formed.

Emulsion polymerization is a method of producing a polymer bead in an aqueous solution using a water-soluble initiator, an emulsifier, and a monomer. By the use of emulsifiers, the particle distribution is narrow, and polymer beads having a particle size of 1 탆 or less are produced. In this regard, US Pat. No. 4,522,953 discloses a technique for preparing porous polystyrene polymer beads by emulsion polymerization.

However, the polystyrene beads have a weak solvent resistance to organic solvents such as toluene, MEK (methylethylketone), and EA (ethyl alcohol) when used as a diffuser for a light diffusion plate or a light diffusion film, (swelling), and there is a problem that yellowing occurs at the time of extrusion or injection.

Thus, while trying to take advantage of the advantages of polystyrene beads and to overcome the disadvantages, the present inventors produced core-shell polymer beads made of polystyrene and shells made of polysilsesquioxane. Such a core-shell polymer bead can have an effect of increasing the brightness due to the high refractive index of the polystyrene particles of the core, and is advantageous in price. In addition, since the shell is composed of polysilsesquioxane and has a structure that is crosslinked with a dense three-dimensional network structure, the specific gravity is low as compared with the organic polymer, and the excellent heat resistance It is confirmed that polysilsesquioxane beads having the characteristic and fluidity can be used to solve the problem of yellowing and solvent resistance of existing polystyrene beads.

Accordingly, an object of the present invention is to provide a core-shell polymer bead having a very uniform particle distribution with a particle size of 1 to 20 μm and a coefficient of variation (CV) of less than 20% overcoming the disadvantages of conventional polystyrene beads, .

In order to achieve the above object, one embodiment of the present invention provides a core-shell polymer bead comprising a core layer made of polystyrene beads and a polyalkyl silsesquioxane shell layer.

In the present invention, the polymer bead has a particle size of 1 to 20 μm and a coefficient of variation (CV) of less than 20%.

Another embodiment of the present invention provides a process for preparing a polymer bead of core-shell structure comprising the steps of:

The ion exchange water, the monomer, the crosslinking agent, the initiator and the stabilizer were added to the reactor, and the mixture was stirred at a high speed to prepare a premixing solution. The solution was vigorously stirred with a homogenizer to prepare a stable particle forming solution. A first step of preparing a core layer bead by suspending; And

An ion exchange water, an acid catalyst and an alkyltrialkoxysilane are added to the core layer beads to hydrolyze them, and an aqueous solution containing ion-exchanged water and a base catalyst is slowly added dropwise to this solution, and the polyalkylsilsesquioxane shell layer . ≪ / RTI >

In still another embodiment of the present invention, a molded article produced by coating the polymer beads may be provided.

Hereinafter, the present invention will be described in more detail.

The polymer bead of the core-shell structure of the present invention basically comprises a core layer consisting of polystyrene beads, and a polyalkyl silsesquioxane shell layer.

The method of producing the polymer bead of the present invention comprises a first step of preparing a polystyrene core layer bead by suspension polymerization as follows and a second step of producing a polysilsesquioxane shell layer by hydrolysis and polycondensation .

Step 1

In the first step, ion-exchanged water, a monomer, a crosslinking agent, an initiator and a stabilizer are added to a reactor and stirred at a high speed to prepare a pre-mixing solution. The solution is discharged from the reactor and homogenizer ) To prepare a stable particle-forming solution. Then, the solution is put into a reactor and the inner temperature is raised to 60 to 90 ° C to prepare a core layer bead. The core layer prepared in this step is preferably made of polystyrene beads and has a degree of crosslinking of 1 to 98%, a particle size of 1 to 20 탆 and a very narrow particle size distribution.

In the present invention, in the preparation of the pre-mixing solution, if the stirring is not performed at a sufficiently high speed, the homogenizer is stable after use and the desired particle formation is not achieved. In addition, when the pre-mixing solution is polymerized immediately after the high-speed stirring without using a homogenizer, aggregation phenomenon occurs, and polymer beads having a particle distribution of 100 μm or more are produced.

The monomer may be at least one selected from the group consisting of aromatic vinyl monomers, acrylic acid or methacrylic acid alkyl ester monomers having 1 to 20 carbon atoms, and acrylic acid or methacrylic acid fluoroalkyl ester monomers having 1 to 20 carbon atoms. The content of the monomer may be 10 to 95 parts by weight based on the total polymer beads.

The crosslinking agent is selected from the group consisting of 1,2-ethanediol diacrylate, 1,3-propanediol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, , 1,6-hexanediol diacrylate, divinylbenzene, ethylene glycol diacrylate, propylene glycol diacrylate, butylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol Diacrylate, polybutylene glycol diacrylate, allyl acrylate, 1,2-ethanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol dimethacrylate, 1 , 4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate, Krill One selected from the group consisting of ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, allyl methacrylate, and diallyl maleate Or more can be used. The content of the crosslinking agent may be 1 to 98 parts by weight based on the whole polymer beads.

The polymer stabilizer may be selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, methylcellulose, ethylcellulose, sodium carboxymethylcellulose, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, sodium polymethacrylate, gelatin, Polyethylene oxide, etc. These may be used alone or in combination of two or more. The content of the polymer stabilizer is preferably 0.2 to 10 parts by weight based on the total polymer beads in consideration of the average particle size and the particle size distribution of the beads.

The initiator can be selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, azobismethylbutyronitrile, and azobiscyclohexanecarbonitrile, and the content thereof is 0.1 to 5.0 parts by weight based on the total polymer beads desirable.

Step 2

In the second step, the ion-exchanged water, the acid catalyst and the alkyltrialkoxysilane are added to the core layer beads prepared in the first step to perform a hydrolysis reaction, and then a solution prepared by mixing ion-exchanged water and an alkali catalyst is added dropwise, Finally, the shell has polystyrene as a core and produces a polymer bead composed of polyalkyl silsesquioxane. At this time, the shell layer is made of polysilsesquioxane having a particle size of 1 to 5 μm, the size of the final particle having a core-shell structure is 1 to 20 μm, the coefficient of variation (CV) is 20% And exhibits a very uniform particle distribution.

In the second step, it is preferable to drop the ion-exchange water and the alkali catalyst mixture solution dropwise over a sufficient time to form a core-shell structure having a desired average particle size and particle size distribution. Further, in the case of stirring, if the stirring is too strong, there is a tendency that the coagulation or fusion of the particles occurs, so that stirring is preferably carried out under possible mild conditions.

After completion of the reaction, the polymer beads are separated by filtration, washed with ion exchange water three to four times, dehydrated and vacuum dried at 70 ° C. for 24 hours to obtain final polymer beads. In some cases, for example, when the particles aggregate at the time of drying, it is preferable to carry out a pulverizing process by a pulverizer such as a jet mill, a ball mill atomizer or a hammer mill.

The alkyltrialkoxysilane compound used in the second step is preferably an alkyltrialkoxysilane having an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Specifically, the alkyltrialkoxysilane may be at least one selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, Vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, vinyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, gamma -acryloyloxypropyltrimethoxysilane, gamma -methacryloxypropyltrimethoxysilane, dimethyldimethoxysilane and methylphenyldimethoxysilane, and it is preferable to use at least one selected from the group consisting of? Of these, methyltrimethoxysilane or vinyltrimethoxysilane, and especially methyltrimethoxysilane, are preferred because of higher reactivity. The amount of the alkyltrialkoxysilane is preferably 5 to 72 parts by weight based on 100 parts by weight of the aqueous medium.

The acid catalyst used for the hydrolysis of the alkyltrialkoxysilane may be an organic acid catalyst such as hydrochloric acid, sulfuric acid, formic acid, acetic acid, propionic acid, oxalic acid and citric acid. The amount of the organic acid catalyst to be used is preferably 0.001 to 1 part by weight based on 100 parts by weight of the aqueous medium. When the amount of the organic acid catalyst is less than 0.001 parts by weight, the hydrolysis reaction does not proceed sufficiently. When the amount of the organic acid catalyst is more than 1 part by weight, the reaction efficiency is lowered as the concentration of the organic acid increases.

The basic catalyst serves to neutralize the organic acid catalyst of the partial hydrolyzate of alkyltrialkoxysilane and is used as a catalyst for condensation polymerization. Examples of the basic catalyst include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide and lithium hydroxide; Alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; Alkali metal carbonates such as potassium carbonate and sodium carbonate; It is possible to use one or two or more kinds selected from the group consisting of monomers such as monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and ammonia. However, it is preferable that the solubility in water and the catalytic activity are excellent , It is more preferable to use ammonia which is low in toxicity and easy to be removed, particularly inexpensive.

The pH of the aqueous solution after the addition of the basic catalyst is in the range of 9.0 to 13.0, and most preferably in the range of 9.5 to 12.0. At this time, if the pH is lower than 9, the rate of condensation polymerization decreases, and the particles tend to flocculate and fuse with each other. As a result, the aqueous suspension can gel, and if the pH is higher than 13.0, the rate of condensation polymerization of the organotrialkoxysilane increases The reaction efficiency is lower than the input amount and the yield is low because an irregular gel is produced.

The hydrolysis reaction and condensation polymerization reaction are preferably carried out at a temperature of 10 to 30 ° C, more preferably 10 to 20 ° C.

The ion-exchanged water to be used in the present invention preferably has a smaller cation number, and more preferably has a resistance value of at least 5 megohm (5M?) Under a nitrogen stream generated through an ion exchanger.

In addition, the present invention can provide a molded article produced using the polymer beads of the core-shell structure produced by the above method, which includes film, extrusion, injection molding, and casting mold. In other words, the polymer bead of the core-shell structure of the present invention can be used as a light diffusing film of a backlight unit (BLU) of a display material field and a light diffusing agent of a light diffusing plate, a surface lubrication property of a coating material field, a water repellency, Anti-blocking agent for film, paint and cosmetic additive. Preferably, the polymer bead of the core-shell structure of the present invention is used for the use of a light diffusing film of a backlight unit (BLU) in a display material field and a light diffusing agent of a light diffusing plate.

The core-shell structure polymer bead according to the present invention has a particle size of 1 to 20 탆 and a particle size distribution with a coefficient of variation (CV) of less than 20%. The core is made of polystyrene and has a high refractive index And the shell is made of polyalkyl silsesquioxane and has excellent thermal stability and excellent solvent resistance.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples. However, the following Examples are provided for easier understanding of the present invention, but the present invention is not limited to these Examples.

<Examples>

In the following Examples and Comparative Examples, the coefficient of variation (C.V. value) was obtained by the following equation using a particle size distribution measuring apparatus (Coulter Electronics, Multisizer 3).

[Equation 1]

C.V. (%) = (standard deviation of particle diameter / average particle diameter of particle) 占 100

&Lt; Example 1 >

Step 1

1014.29 g of ion-exchanged water and 8 g of polyvinyl alcohol (Mw = 10,000) were placed in a 2 L reactor and stirred. 438.8 g of styrene monomer, 6.64 g of 1,6-hexanediol diacrylate and 1.5 g of azobisisobutyronitrile were placed in this reactor and stirred at a speed of 700 rpm for 30 minutes. The pre-mixing solution was discharged from the reactor and subjected to strong agitation twice at a homogenizer pressure of 4000 psi. This solution was further charged into a 2 L reactor and heated at 60 ° C. for 7 hours while stirring at 250 rpm under a nitrogen stream. The mixture was filtered, washed, dehydrated and dried to obtain a core layer polymer bead . The mean particle size of the polystyrene beads thus prepared was 5.3 탆 and the C.V. was 15.3%, which was referred to as core particles.

Step 2

360 g of the core particles prepared in the first step, 630 g of ion-exchanged water and 0.4 g of acetic acid were added while the nitrogen was purged into a 2 L round-bottomed flask, and the mixture was stirred at 200 rpm for 30 minutes. After stirring for 30 minutes, 420 g of methyltrimethoxysilane was added and stirred at 200 rpm. The internal temperature of the mixed solution was increased to 40 ° C. after 6 minutes, and after about 5 hours, the methyltrimethoxysilane was completely dissolved to obtain a homogeneous partial hydrolyzate. After the solution thus obtained was cooled to 18 캜, a solution prepared by mixing 0.8 g of 29% ammonia aqueous solution and 490 g of ion-exchanged water was slowly added dropwise over 3 hours. At this time, the reaction temperature was maintained at 18 ° C, and condensation polymerization was carried out while stirring at a stirring speed of 50 rpm to produce a polymer bead having polyalkylsilsesquioxane as a shell.

The thus-obtained polymer beads were filtered, washed three times with ion exchange water, dehydrated and vacuum-dried at 70 DEG C for 24 hours to finally obtain a polymer bead having polystyrene as a core and polyalkylsilsesquioxane as a shell . The polymer beads of the core-shell structure thus prepared had an average particle size of 7.2 탆 and a C.V. of 13.3%. Fig. 3 shows SEM analysis photographs of the polymer beads.

&Lt; Example 2 >

Polymer beads were prepared in the same manner as in Example 1 except that 12 g of polyvinyl alcohol was used instead of 8 g of polyvinyl alcohol in the first step. The particle size of the polymer beads of the finally prepared core-shell structure was 6.3 탆, and C.V, was 10.5%.

&Lt; Example 3 >

Polymer beads were prepared in the same manner as in Example 1 except that 420 g of vinyltrimethoxysilane was used instead of 420 g of methyltrimethoxysilane in the second step. The particle size of the polymer beads of the finally prepared core-shell structure was 8.6 탆 and the C.V. was 21.3%.

&Lt; Comparative Example 1 &

1014.29 g of ion-exchanged water and 8 g of polyvinyl alcohol (Mw = 10,000) were placed in a 2 L reactor and stirred. 438.8 g of styrene monomer, 6.64 g of 1,6-hexanediol diacrylate and 1.5 g of azobisisobutyronitrile were placed in this reactor and stirred at a speed of 700 rpm for 30 minutes. The pre-mixing solution was discharged from the reactor and subjected to homogenization twice at 4000 psi pressure. This solution was further charged into a 2-liter reactor and heated at 60 ° C. for 7 hours while stirring at 250 rpm under a nitrogen stream. The mixture was filtered, washed, dehydrated and dried to prepare polymer beads Respectively. The mean particle size of the polystyrene beads thus prepared was 5.3 탆 and the C.V. was 15.3%, and the second step was not carried out.

<Experimental Example>

Evaluation of Stability and Solvent Resistance of Polymer Beads Prepared by Core-Cell Method

(TOL, MEK) were prepared for the Example 1 and the Comparative Example 1, and the stability was evaluated after the initial time, 1 hour, 2 hours, 3 hours, 4 hours, 6 hours, 8 hours and 24 hours Respectively.

The stability was evaluated at a fixed time of 50 rpm using Brookfield viscometer spindle No. 2, and the measured value was expressed in terms of viscosity (cP%).

Table 1 and FIG. 1 show the result of evaluating the stability of a solution prepared by using the respective particles prepared in Example 1 and Comparative Example 1 together with a solvent TOL. Table 2 and FIG. 2 show the result of evaluating the stability of the crude liquid prepared with the solvent MEK using each of the particles prepared in Example 1 and Comparative Example 1.

Category (hr) Example 1 Comparative Example 1


TOL 0 3.6 16.2 One 3.6 15.0 2 3.6 16.8 3 3.6 28.2 4 3.6 38.4 6 4.2 59.2 8 4.2 79.4 24 5.4 105.6

Category (hr) Example 1 Comparative Example 1


MEK 0 1.8 2.4 One 2.4 5.4 2 3 14.4 3 3 79.8 4 3 99.0 6 3 113.4 8 3.6 130.2 24 4.8 196.2

From the results of Tables 1 and 2 and FIGS. 1 and 2, the stability was maintained even after 24 hours in the case of using the particles prepared in Example 1, whereas in the case of using the particles prepared in Comparative Example 1, The stability was broken in time and the particles settled and solidified.

The polymer beads of the core-shell structure of the present invention are excellent in refractive index, thermal stability and solvent resistance, so that the light diffusing film of the backlight unit (BLU) of the display material field and the light diffusing agent of the light diffusing plate, , Water repellency, oil repellency-imparting agent, anti-blocking agent for plastic film, paint and cosmetic additive.

Fig. 1 shows the stability evaluation results of the polymer beads according to Example 1 and Comparative Example 1 against TOL (toluene).

2 shows the stability evaluation results of the polymer beads according to Example 1 and Comparative Example 1 against MEK (methyl ehtyl ketone).

3 is an SEM analysis photograph of Example 1. Fig.

Claims (15)

A core layer made of polystyrene beads, and a polyalkyl silsesquioxane shell layer, A particle size of 1 to 20 mu m, a coefficient of variation (CV) of less than 20% Wherein the polyalkyl silsesquioxane shell layer is made of polysilsesquioxane having a thickness of 1 to 5 占 퐉. delete 2. The polymer bead of claim 1, wherein the polystyrene core bead layer has a core-shell structure having a degree of crosslinking of 1 to 98% and a particle size of 1 to 20 m. delete The polymer bead according to claim 1, wherein the polymer bead is used for the use of a light diffusing film of a backlight unit (BLU) in the field of display materials and a light diffusing agent of a light diffuser plate. CLAIMS What is claimed is: 1. A laminate comprising a core layer made of polystyrene beads and a polysilsesquioxane shell layer having a thickness of 1 to 5 占 퐉, the layer having a particle size of 1 to 20 占 퐉, a coefficient of variation (CV) of less than 20% &Lt; RTI ID = 0.0 &gt; of: &lt; / RTI &gt; A pre-mixing solution is prepared by adding ion-exchanged water, a monomer, a crosslinking agent, an initiator and a stabilizer to the reactor, stirring the solution with a homogenizer to prepare a particle forming solution, suspending it at 60 to 90 ° C A first step of producing a core layer bead; And An ion exchange water, an acid catalyst and an alkyltrialkoxysilane are added to the core layer beads to hydrolyze them, an aqueous solution containing ion-exchanged water and a base catalyst is added dropwise to the solution, and a polyalkylsilsesquioxane shell layer A second step of manufacturing, The monomer is at least one selected from the group consisting of aromatic vinyl monomers, acrylic acid or methacrylic acid alkyl ester monomers having 1 to 20 carbon atoms, and acrylic acid or methacrylic acid fluoroalkyl ester monomers having 1 to 20 carbon atoms. The method for producing a polymer bead of core-shell structure according to claim 6, wherein the alkyltrialkoxysilane is an alkyltrialkoxysilane having an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. The method for producing a polymer bead according to claim 7, wherein the alkyltrialkoxysilane is used in an amount of 5 to 72 parts by weight based on 100 parts by weight of ion-exchanged water. 7. The composition of claim 6, wherein the stabilizer is selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, methylcellulose, ethylcellulose, sodium carboxymethylcellulose, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, sodium polymethacrylate, Gelatin, polyacrylamide, and polyethylene oxide. The method of producing the polymer bead of core-shell structure according to claim 1, wherein the polymer bead is at least one selected from the group consisting of gelatin, polyacrylamide and polyethylene oxide. delete 7. The composition of claim 6, wherein the crosslinking agent is selected from the group consisting of 1,2-ethanediol diacrylate, 1,3-propanediol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, Diethylene glycol diacrylate, butylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, diethylene glycol diacrylate, diethylene glycol diacrylate, diethylene glycol diacrylate, Acrylate, polypropylene glycol diacrylate, polybutylene glycol diacrylate, allyl acrylate, 1,2-ethanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol di Methacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, Butylrangle Polyacrylic acid, methacrylic acid, methacrylic acid, acrylic acid, methacrylic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic anhydride, &Lt; / RTI &gt; wherein said at least one polymeric bead is at least one selected from the group consisting of polymeric beads. 7. The method of producing a polymer bead according to claim 6, wherein the acid catalyst is selected from the group consisting of hydrochloric acid, sulfuric acid, formic acid, acetic acid, propionic acid, oxalic acid and citric acid. The method according to claim 6, wherein the base catalyst is selected from the group consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide, potassium carbonate, sodium carbonate, monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and ammonia &Lt; / RTI &gt; wherein the core-shell structure is selected from the group consisting of: The method of producing a polymer-bead according to claim 6, wherein the polycondensation reaction is performed at a temperature of 10 to 30 占 폚. A molded article produced by coating the polymer bead according to claim 1.

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