KR101409467B1 - Polymeric beads having a good thermal stability in the high temperature conditions - Google Patents

Abstract

The present invention relates to a polymer bead having excellent optical properties and enhanced heat resistance, and more particularly to a polymer bead having an aromatic vinyl monomer, an acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms and an acrylic acid or methacrylic acid having 1 to 20 carbon atoms At least one monomer selected from the group consisting of acrylic acid, methacrylic acid, and acrylic acid; A carboxylic acid compound having 1 to 20 carbon atoms; A crosslinking agent; Initiator; And ion-exchanged water, and has at least one endothermic peak at 160 캜 or higher in differential scanning calorimetry (DSC) analysis, and has a weight loss of 10% by weight in thermogravimetric analysis (TGA) RTI ID = 0.0 > 255 C. < / RTI >

Polymer beads, heat resistance, internal crystallinity, color change

Description

POLYMERIC BEADS HAVING A GOOD THERMAL STABILITY IN THE HIGH TEMPERATURE CONDITIONS < RTI ID = 0.0 >

TECHNICAL FIELD The present invention relates to a polymer bead having enhanced heat resistance, and more particularly, to a polymer bead having excellent optical properties and excellent thermal stability at a high temperature.

Polymer particles are collectively referred to as spherical particles having a uniform particle size distribution produced by emulsion polymerization or suspension polymerization. The polymer particles have a wide variety of applications, 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.

Polymer particles used for this purpose such as polystyrene beads and the like are generally prepared by methods such as suspension polymerization, dispersion polymerization and emulsion polymerization.

In conventional suspension polymerization, 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. 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.

Since the polymer particles produced through the conventional polymerization process have different refractive indexes from those of conventional resins, they can provide hiding power, and thus they are widely used in extruding and manufacturing a light diffusion plate or a lighting fixture. As the product is made by extrusion, it is required to have excellent thermal stability because the product is used by mixing at a high temperature. However, when such a conventional polymer bead is stagnated at high temperature for 30 minutes or more, the weight loss reduction width is large, which may lead to physical and chemical changes to the environment in which the bead is used. That is, there may be a change in physical properties of the final product due to lowered compatibility, fume or byproducts, and there is a problem in that the physical properties such as the shape of particles are seriously deformed when read by SEM photograph.

Therefore, when applied to various applications such as a light diffusion film, it is possible to improve the heat at an elevated temperature with excellent optical characteristics so as to minimize the occurrence of color change and fume, It is necessary to study the development of polymer beads with stability.

The present invention aims to provide a polymer bead having both good optical properties and heat resistance.

The present invention relates to a resin composition comprising at least one monomer 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 fluoroalkyl methacrylate monomers having 1 to 20 carbon atoms; A carboxylic acid compound having 1 to 20 carbon atoms; A crosslinking agent; Initiator; And ion-exchanged water, and has at least one endothermic peak at 160 캜 or higher in differential scanning calorimetry (DSC) analysis, and has a weight loss of 10% by weight in thermogravimetric analysis (TGA) Thereby providing a polymer bead having a temperature of 255 DEG C or higher.

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

The present inventors have made efforts to provide polymer beads with excellent optical properties and improved thermal stability at a high temperature, and have found that, in addition to a predetermined monomer, a desired carboxylic acid compound, a crosslinking agent, an initiator, The polymer beads are prepared using the composition and have excellent physical properties and heat resistance by having a physical property measurement value in a predetermined range or more in differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) Can be produced.

Particularly, in the present invention, by adding a predetermined carboxylic acid compound together with a crosslinking agent, an initiator and the like in the step of producing a polymer bead having excellent optical properties by using a predetermined monomer, not only the increase in bonding in the polymer chain direction It is possible to increase the bonding force between the polymer chain and the chain and consequently to impart crystallinity and to produce polymer beads having excellent optical properties and improved thermal stability at high temperatures.

The inner crystalline polymer bead of the present invention basically refers to a bead composed of polymethylmethacrylate beads, polystyrene beads, polyurethane beads and the like. Of these, the polymethacrylate beads and the like are more preferable examples in terms of optical properties .

According to an embodiment of the present invention, the present invention provides a method of measuring a physical property of a sample, which is manufactured from a composition having a predetermined composition and is subjected to differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) Is provided. Such polymer beads include one or more monomers 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 fluoroalkyl methacrylate monomers having 1 to 20 carbon atoms; A carboxylic acid compound having 1 to 20 carbon atoms; A crosslinking agent; Initiator; And ion-exchanged water, and has at least one endothermic peak at 160 캜 or higher in differential scanning calorimetry (DSC) analysis, and has a weight loss of 10% by weight in thermogravimetric analysis (TGA) The temperature may be 255 DEG C or higher.

In particular, the polymer beads of the present invention may have one or more endothermic peaks at 160 ° C. or higher, or 160 ° C. to 300 ° C., preferably 180 ° C. or higher, or 180 ° C. to 250 ° C. in differential scanning calorimetry (DSC) . In the differential scanning calorimetry (DSC) analysis, when at least one endothermic peak does not appear at 160 ° C or more, the polymer bead is not imparted with the internal crystallinity, so that the thermal stability at the time of heat treatment at the high temperature is lowered, I can not keep it.

The polymer bead of the present invention has one or more endothermic peaks at 160 ° C or higher in differential scanning calorimetry (DSC) analysis, thereby imparting internal crystallinity and securing excellent thermal stability along with excellent optical properties . In particular, in the case of the polymer bead, an endothermic peak is found at a high temperature of 160 ° C or more in the primary scan in the DSC measurement, but no endothermic peak is observed in the secondary scan. In the bead of the present invention, the bond type represented by the endothermic peak is not a polymer chain-forming bond but a bond type that can appear between a polymer chain and a chain, i.e., a form such as a hydrogen defect, .

In addition, the polymer bead may have a weight loss of 10 wt% or more at 255 ° C or 255 to 400 ° C, preferably 260 to 350 ° C at the time of thermogravimetric analysis (TGA). When the weight loss of the polymer beads is less than 255 ° C at a weight loss of 10 wt% in a thermogravimetric analysis (TGA), discoloration may occur after heat treatment at a high temperature, and excellent heat resistance It can be difficult to maintain.

The polymer bead of the present invention is made of a composition comprising a polymer monomer, a carboxylic acid compound having 1 to 20 carbon atoms, a crosslinking agent, an initiator, and an ion exchange water.

At this time, the monomer may be at least one selected from the group consisting of an aromatic vinyl monomer, an acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, and an acrylic acid or a methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms For example, methyl methacrylate, styrene, divinyl benzene, butyl methacrylate, trimethylolmethane tetraacrylate, trimethylol methane, Trimethylolmethane triacrylate, trimethylolbutane triacrylate, ethylene glycol dimethacrylate, and the like can be used. Of these monomers, methyl methacrylate, styrene, divinylbenzene, and butyl methacrylate are preferred from the viewpoint of securing excellent optical properties of the polymer beads.

The content of the monomer may be 10 to 50% by weight, preferably 20 to 40% by weight, more preferably 30% by weight based on the total composition. The monomer content may be 10 wt% or more in terms of controlling the particle size, and may be 50 wt% or less in terms of increasing the degree of crosslinking. The content of such a monomer may be 10 to 95 parts by weight, preferably 50 to 95 parts by weight, more preferably 80 to 95 parts by weight, based on the finally prepared polymer beads.

The carboxylic acid compound may be selected from the group consisting of methacrylic acid, acetic acid, methaconic acid, citric acid, itaconic acid, acrylic acid, ascorbic acid, acetic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, phthalic acid, May be at least one selected from the group consisting of isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, and the like. The carboxylic acid compound is preferably a compound containing a carboxyl group (Acid functional group) in the terminal group, in particular, from the viewpoint of improving the degree of crosslinking of the polymer bead. When the polymerization stability is considered in the above compounds, methacrylic acid, acetic acid and the like are more preferable.

The content of the carboxylic acid compound may be 1 to 15 parts by weight, preferably 1.5 to 7 parts by weight, more preferably 3 to 5 parts by weight based on 100 parts by weight of the monomer. The content of the carboxylic acid compound may be 1 part by weight or more in view of imparting internal crystallinity, and may be 15 parts by weight or less in view of polymerization stability. At this time, the content of the carboxylic acid compound is preferably maintained such that the viscosity of the additive is maintained so that polymer beads having excellent optical properties can be produced from the monomers. When the content of the carboxylic acid compound is excessively over the above content range, It may become involved in the reaction, and thus it may become difficult to produce polymer beads having desired excellent optical properties. The content of the carboxylic acid may be 1 to 10 parts by weight, preferably 1.5 to 7 parts by weight, more preferably 3 to 5 parts by weight, based on the polymer beads finally prepared.

Also, the crosslinking agent may be at least one selected from the group consisting of 1,2-ethanediol diacrylate, 1,3-propanediol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, Acrylate, 1,6-hexanediol diacrylate, divinylbenzene, ethylene glycol diacrylate, propylene glycol diacrylate, butylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, poly Propylene glycol diacrylate, propylene 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 di Meta Polypropylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, At least one selected from the group consisting of glycol dimethacrylate, polybutylene glycol dimethacrylate, allyl methacrylate, diallyl maleate, and trimethylolpropane triacrylate (TMPTA) can be used . Of these, 1,2-ethanediol diacrylate, ethylene glycol diacrylate, triethylene glycol diacrylate and the like are more preferable from the viewpoint of polymerization stability.

The content of the crosslinking agent may be 1 to 98 parts by weight, preferably 5 to 50 parts by weight, more preferably 8 to 30 parts by weight based on 100 parts by weight of the monomer. The content of the crosslinking agent may be 1 part by weight or more in view of enhancing the solvent resistance, and may be 98 parts by weight or less in terms of polymerization yield. The content of such a cross-linking agent may be 1 to 98 parts by weight, preferably 5 to 50 parts by weight, more preferably 8 to 30 parts by weight based on the polymer beads finally prepared.

Wherein the initiator is selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, azobiscenyl butyronitrile, azobiscyclohexanecarbonitrile, potassium persulfate, sodium persulfate, ammonium persulfate, and azo based water- A peroxide compound such as benzoyl peroxide, lauryl peroxide, octanoyl peroxide, or dicumyl peroxide, may be selected and used. Of these, benzoyl peroxide, azobisisobutyronitrile, azobiscenyl butyronitrile and the like are more preferable in terms of polymerization stability.

The polymerization initiator is preferably used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the total amount of the monomers. If the content is less than 1 part by weight, unreacted monomers may be excessively produced. If the amount is more than 5 parts by weight, there is a problem that the polymerization stability is deteriorated due to rapid heat generation.

In addition, a dispersion stabilizer may be further added to the polymer bead composition for suspension stabilization. Examples of the dispersion stabilizer include polyvinyl alcohol, polyvinyl pyrrolidone, methylcellulose, ethylcellulose, sodium carboxymethylcellulose, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, sodium polymethacrylate, gelatin, A mixture of at least one member selected from the group consisting of polyacrylamide, polyethylene oxide, polyvinyl methyl ether, polyethyleneimide, vinyl acetate copolymer, hydroxypropyl cellulose, silica and siloxane can be used. Particularly, from the viewpoint of polymerization stability, polyvinyl alcohol, polyvinyl methyl ether, vinyl acetate copolymer and the like are more preferable.

The content of the dispersion stabilizer may be 1 to 50 parts by weight, preferably 1 to 10 parts by weight based on 100 parts by weight of the monomer. If the content of the dispersion stabilizer is less than 1 part by weight, the stability of emulsification is poor and a large amount of polymer flocculant is generated. When the content of the dispersion stabilizer is more than 50 parts by weight, it is difficult to remove the dispersion stabilizer in the cleaning process of the polymer bead .

In addition, the composition includes ion exchanged water together with a monomer, a carboxylic acid compound, a crosslinking agent, an initiator and the like. The ion-exchanged water used in the present invention preferably has a smaller cation number, and more preferably has a resistance value of at least 5 M OMEGA under a nitrogen stream generated through an ion exchanger. The ion-exchanged water may be added in an amount other than the total amount of monomers, carboxylic acid compounds, crosslinking agents, initiators, and the like, relative to the total composition. Preferably, May be added in a controlled amount to a level suitable for the process of producing the catalyst.

On the other hand, in view of ensuring both excellent optical properties and thermal stability at high temperatures of the polymer bead of the present invention, the composition may contain an aromatic vinyl monomer, an acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, 100 parts by weight of at least one monomer selected from the group consisting of 20 acrylic acid or fluoroalkyl methacrylate monomers, 1 to 15 parts by weight of a carboxylic acid compound having 1 to 20 carbon atoms, 1 to 98 parts by weight of a crosslinking agent, To 5 parts by weight, and ion-exchanged water.

The composition for preparing a polymer bead may further comprise a monomer selected from the group consisting of an aromatic vinyl monomer, an acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, and an acrylic acid or a methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms. 100 parts by weight of monomers or more, 1 to 15 parts by weight of a carboxylic acid compound having 1 to 20 carbon atoms, 1 to 98 parts by weight of a crosslinking agent, 1 to 5 parts by weight of an initiator, 1 to 50 parts by weight of a dispersion stabilizer, It may be.

The polymer beads of the present invention are prepared using the above composition, and in particular, can be produced by reacting an aromatic vinyl monomer, an acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms and an acrylic acid or methacrylic acid fluoroalkyl ester having 1 to 20 carbon atoms And a step of polymerizing a suspension prepared by mixing at least one monomer selected from the group consisting of monomers, carboxylic acid compounds having 1 to 20 carbon atoms, a crosslinking agent, an initiator, and ion exchange water.

In a more preferred embodiment, the present invention can produce a polymer bead by preparing a monomer solution containing a monomer and an initiator and then suspending the monomer solution in water to polymerize. In this case, the polymeric bead in which the crystallinity is imparted to the interior of the monomer solution during the preparation of the monomer solution, and hydrogen bond is given to the inside of the polymeric bead, thereby enhancing heat resistance properties compared to conventional spherical polymer beads. Particularly, the present invention relates to a method for producing a polymer bead in which spherical polymer beads are prepared by suspension polymerization, and a carboxylic acid compound is added to impart crystallinity, for example, to a polymer having a degree of crosslinking of 1% to 98% and an average particle size of 1 to 50 탆 And has an extremely uniform particle distribution with a coefficient of variation (CV) of 30% or less, and has an endothermic peak at 160 ° C or higher depending on the formation of internal crystallinity, etc., and a 10% And the polymer beads having thermostability imparted thereto can be produced without changing the shape of the beads or substantially reducing the change in weight even at a stagnation of 30 minutes or more at a high temperature of 250 DEG C or more.

In preparing the polymer bead of the present invention, the suspension may be prepared by mixing a monomer, a carboxylic acid compound, a crosslinking agent, an initiator, and ion-exchanged water at a stirring speed of 100 to 600 rpm, preferably 200 to 500 rpm, Followed by stirring at 250 to 300 rpm. Further, the suspension is further subjected to a step of mixing the monomer, the carboxylic acid compound, the cross-linking agent, the initiator, and the ion-exchanged water and stirring the mixture at a high speed in a homomixer at 1,000 to 6,000 rpm, more preferably 2,000 to 4,000 rpm May be manufactured. At this time, if the suspension is not stirred at a sufficiently high speed in the production, even if a homomixer is used, stable formation of desired particles may not be achieved. In addition, when the suspension is polymerized immediately after the high-speed stirring, aggregation may occur. By using the homomixer with sufficient agitation as described above, such aggregation phenomenon can be effectively prevented, The production of very wide polymer beads can be minimized.

The step of polymerizing the suspension may be carried out at a reaction temperature of 60 ° C to 90 ° C and may be carried out at a stirring speed of 100 to 600 rpm, preferably 200 to 500 rpm, more preferably 250 to 300 rpm Can be performed.

The polymer beads having undergone the polymerization reaction as described above are separated by filtration, washed with ion exchange water three to four times, dehydrated and vacuum dried at 70 DEG 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.

In the present invention, polymer beads having excellent optical properties and improved thermal stability at high temperatures can be prepared by adding a carboxylic acid compound and imparting crystallinity in the step of preparing spherical polymer beads by suspension polymerization.

On the other hand, the polymer bead of the present invention has an average particle diameter of 1 to 50 탆, preferably 1 to 40 탆, more preferably 5 to 30 탆, and a coefficient of variation (CV) of 30% Or 5% to 30%, preferably 25% or less, more preferably 20% or less. The polymer beads having such a particle size and a coefficient of variation can secure properties excellent in optical characteristics in terms of film processing stability and can be effectively used for materials for LCD backlight.

The polymer beads may have a degree of crosslinking of 1% to 98%, preferably 1% to 50%. Although the degree of crosslinking is basically dependent on the crosslinking agent, in the case of the present invention, it is possible to obtain a degree of crosslinking in which the degree of internal crystallization imparted by the bonding between the polymer chain and the chain is further improved, Thermal stability can be ensured.

The polymer bead may have a weight change loss rate of less than 15%, preferably less than 12%, more preferably less than 5% after heat treatment at 250 ° C for 30 minutes, which is about 40% of conventional polymer beads And the heat stability is remarkably improved as compared with the case where the weight change is reduced.

Also, the polymer bead may have a Δb * value of 15 or less, or 0 to 15, preferably 13 or less, more preferably 10 or less, according to a colorimetric measurement after heat treatment at 250 ° C. for 30 minutes. At this time, the value of DELTA L * after the heat treatment may be -20 to 0, preferably -17 to 0, more preferably -15 to 0, and the value of DELTA a * But the absolute value of the? A * value may preferably be 2.0 or less or 2.0 to 0, more preferably 1.5 or less. In view of being able to exhibit excellent optical characteristics when applied to a backlight unit (BLU) for use in an optical display, such as the Δb * value, the ΔL * value, and the Δa * value, * Minimizing the value and preventing yellowing can be more important. Particularly, the polymer bead of the present invention having such a minimized color change value can secure excellent properties in optical characteristics in view of film processing stability and can obtain excellent effects in terms of prevention of yellowing upon extrusion.

On the other hand, as described above, the present invention can provide a molded article produced by using polymer beads effectively imparted with internal crystallinity, which includes film, extrusion, injection, and cast molding. That is, the polymer bead having the internal crystallinity of the present invention can be used as a light diffusing agent for a light diffusing film of a backlight unit (BLU) in a field of display materials, a light diffusing agent for a light diffusing plate, and a cover for illumination. Preferably, the polymer bead with internal crystallinity of the present invention has better heat resistance than conventional beads, and therefore, it is preferably used for a light diffusion plate for extrusion or injection or a light diffusion agent for a cover for illumination.

In the present invention, matters other than those described above can be added or subtracted as required, and therefore, the present invention is not particularly limited thereto.

The present invention relates to a process for preparing a composition containing a monomer, a carboxylic acid compound, a crosslinking agent, an initiator and ion exchanged water in a predetermined composition and performing differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) Analysis, it is possible to effectively produce polymer beads having excellent optical properties such as refractive index, minimization of color change at high temperature, and improved thermal stability by imparting internal crystallinity to the polymer bead itself by having a predetermined range of physical property values .

The polymer beads produced according to the present invention have substantially no physical chemical change even in a heat treatment process at a high temperature, so that fume generation, which is a problem in manufacturing various products such as electronic parts, can be minimized or minimized, It is possible to effectively exhibit the excellent physical properties required for the beads without adversely affecting the physical and chemical properties of the beads.

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

Example  One

As shown in the following Table 1, 100 parts by weight (386.6 g) of methylmethacrylate (MMA), 12 parts by weight (46.4 g) of ethylene glycol dimethacrylate (EGDMMA), and azobisisobutylo A suspension was prepared by mixing 1 part by weight of azobisisobutyronitrile (ABIBN) (3.8 g), 3 parts by weight of methacrilic acid (MAA) (11.6 g) and ion exchanged water (918.13 g) And the mixture was stirred at a speed of 700 rpm for 30 minutes. The suspension was discharged from the reactor and repeated twice at 4,000 rpm in a homomixer to perform strong stirring. The suspension was poured into a 2 L reactor, heated at 60 rpm at 250 rpm under nitrogen flow, reacted at 60 DEG C for 7 hours, filtered, washed, dehydrated and dried 386 g of polymer beads were prepared.

Example  2 to 4

As shown in the following Table 1, except that the content of methacrilic acid (MAA) was increased by 2% to 10%, respectively, to 5 parts by weight, 7 parts by weight and 10 parts by weight, respectively, 382 g, 380 g, and 379 g of polymer beads, respectively, were prepared in the same manner.

Example  5 ~ 8

As shown in the following Table 1, methaconic acid (MCA), acetic acid, AcA, acrylic acid (AA) and ascorbic acid (MAA) were used instead of methacrilic acid , AsA) was used as a polymerization initiator, 280 g of a polymer bead was prepared.

Example  9-11

As shown in the following Table 1, different types of monomers, cross-linking agents and initiators were used, and styrene, trimethylolpropane triacrylate (TMPTA), benzoyl peroxide (BZPO), polyvinyl alcohol , PVA), 300 g of polymer beads were prepared in the same manner as in Example 1. [

Example  12

As shown in the following Table 1, 354 g of a polymer bead was obtained in the same manner as in Example 1 except that polyvinyl alcohol as a dispersion stabilizer was further added in an amount of 6 parts by weight based on 100 parts by weight of the monomer and mixed to prepare a suspension. .

Comparative Example  One

As shown in the following Table 1, 380 g of a polymer bead was prepared in the same manner as in Example 1, except that methacrilic acid was not added.

The compositions for preparing the polymer beads of Examples 1 to 12 and Comparative Example 1 are shown in Table 1 below. Each content unit is parts by weight.

division Monomer Carboxylic acid Cross-linking agent Initiator Dispersion stabilizer ingredient content ingredient content ingredient content ingredient content ingredient content Example 1 MMA 100 MAA 3 EGDMMA 12 ABIBN One - - Example 2 MMA 100 MAA 5 EGDMMA 12 ABIBN One - - Example 3 MMA 100 MAA 7 EGDMMA 12 ABIBN One - - Example 4 MMA 100 MAA 10 EGDMMA 12 ABIBN One - - Example 5 MMA 100 MCA 3 EGDMMA 12 ABIBN One - - Example 6 MMA 100 AcA 3 EGDMMA 12 ABIBN One - - Example 7 MMA 100 AA 3 EGDMMA 12 ABIBN One - - Example 8 MMA 100 Asa 3 EGDMMA 12 ABIBN One - - Example 9 MMA 100 MAA 3 TMPTA 12 ABIBN One - - Example 10 MMA 100 MAA 3 EGDMMA 12 BZPO One - - Example 11 Styrene 100 MAA 3 EGDMMA 12 ABIBN One - - Example 12 MMA 100 MAA 3 EGDMMA 12 ABIBN One PVA 6 Comparative Example 1 MMA 100 - - EGDMMA 12 ABIBN One - -

The properties of the polymer beads prepared according to Examples 1 to 12 and Comparative Example 1 were measured by the following methods, and the measured physical properties are summarized in Table 2 below.

a) Average particle diameter  And the coefficient of variation (C.V .: Coefficient of variation )

The average particle diameter of the polymer beads was measured by using a particle size distribution measuring apparatus (Multisizer 3, manufactured by Coulter Electronics Co., Ltd.), and the coefficient of variation (C.V.) was calculated by the following equation.

[Equation 1]

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

b) Evaluation of crystallinity

The crystallinity of polymer beads was measured by DSC (Differential Scanning Calorimeter) analysis method, and this crystallinity evaluation method can be known when the beads are observed by thermal change using a DSC analyzer. Particularly, it can be seen that when the DSC analysis is performed, the internal crystallization is imparted to the interior, and there is an endothermic reaction at a high temperature (160 ° C or higher). In the case where internal crystallinity is imparted, an endothermic peak is found at a high temperature (160 ° C or higher) in the primary scan as a result of DSC measurement, but no such endothermic peak is observed in the secondary scan.

Accordingly, the heat flow (w / g) was measured by DSC analysis, and the temperature at which the endothermic peak occurred at 200 ° C or more was confirmed.

The results of DSC analysis of the polymer beads prepared in Example 1 and Comparative Example 1 are shown in FIG.

c) weight change at high temperature Weight loss rate  evaluation

The weight loss rate of the polymer beads was measured by using a heat loss weight analysis method. The heat loss weight analysis was carried out by placing 8 g of polymer beads in a 250 ° C. oven in a crucible, measuring the degree of weight loss after stagnation for 30 minutes, As shown in the following equation (2).

[Equation 2]

d) TGA  evaluation

TGA was measured for the polymer beads to confirm the temperature at the point of 10% reduction. Particularly, the TGA measurement was performed under air condition. After heating at 30 ° C to 250 ° C, the temperature rise at 250 ° C was stopped, and the temperature was increased from 250 ° C to 600 ° C. At 250 ° C, I assumed the time to stagnate. A graph of the TGA measurement result is shown in FIG. 2, and a point at which the weight of the polymer bead is reduced by 10% is shown in Table 2 below.

e) High temperature After processing SEM  Measure

The polymer beads of Example 1 and Comparative Example 1 were respectively placed in a crucible and stood in an oven at 250 캜 for 30 minutes, and FE-SEM measurement was carried out as shown in Figs. 3 and 4, respectively.

division Average particle diameter
(탆) CV
(%) High endothermic peak
(° C) Weight change loss rate
(After heat treatment at 250 占 폚 / 30 min,%) 10% reduction temperature
(° C) Example 1 25 18 230 3.5 330 Example 2 25 17 240 4.2 321 Example 3 25 19 210 5.6 310 Example 4 25 16 190 9.8 270 Example 5 25 18 220 10 268 Example 6 24 17 225 12 265 Example 7 25 17 223 10 265 Example 8 25 18 212 13.5 260 Example 9 25 16 220 5.9 300 Example 10 24 18 230 6.2 318 Example 11 25 17 225 4.6 325 Example 12 25 17 210 6.2 310 Comparative Example 1 25 20 - 47.97 250

The polymer beads prepared according to Examples 1 to 12 and Comparative Example 1 were subjected to color change evaluation according to visual evaluation and color change evaluation at high temperature using a color difference meter. At this time, the color change evaluation at high temperature was carried out by placing 8 g of polymer beads in a 250 DEG C oven, and measuring color change after stagnation for 30 minutes was measured by a JISZ 8729 method using a visual evaluation and a colorimeter (NIPPON DENSHOKU SD5000) .

As shown in FIG. 5, in the CIE 1976 standard color coordinates according to the L * a * b * expression method, L * is an index that defines brightness, white becomes white to 100, black becomes black to 0, and a * , RED to +, Green to B -, B * to exponent representing Yellow and Blue, and Yellow to Blue. Among them, the yellowing index (Yellow index) of the polymer bead was determined by the change of the b * value (? B * value).

The color change evaluation results of the polymer beads prepared according to Examples 1 to 12 and Comparative Example 1 at high temperatures are shown in Table 3 below. 6 and 7 are photographs of color change measurement after heat treatment of the polymer beads of Example 1 and Comparative Example 1, respectively.

division L * a * b * ? B * Visual evaluation Early After heat treatment Early After heat treatment Early After heat treatment Example 1 98.04 96.25 -0.12 -0.13 1.45 3.74 2.29 No discoloration Example 2 98.15 96.14 -0.19 -0.22 0.57 3.65 3.08 No discoloration Example 3 98.05 94.02 -0.15 -0.21 0.59 4.22 3.63 No discoloration Example 4 97.73 90.04 -0.86 -1.20 2.41 8.97 6.56 No discoloration Example 5 96.68 90.05 -0.80 -1.00 2.85 9.05 6.2 No discoloration Example 6 98.02 90.69 -0.80 -0.98 2.26 9.06 6.8 No discoloration Example 7 98.04 87.65 -0.76 -0.88 2.37 8.05 5.68 No discoloration Example 8 97.15 87.02 -1.25 -1.34 2.86 12.06 9.2 No discoloration Example 9 97.75 93.08 -0.18 -0.22 0.53 4.05 3.52 No discoloration Example 10 97.73 90.02 -0.21 -0.41 2.29 6.85 4.56 No discoloration Example 11 98.08 93.06 -0.12 -0.17 1.40 4.65 3.25 No discoloration Example 12 96.08 89.98 -0.14 -0.18 2.46 7.02 4.56 No discoloration Comparative Example 1 97.24 74.52 -0.12 -2.54 0.62 26.19 25.27 Discolored

As shown in Table 2, the polymer beads of Examples 1 to 12 prepared using the carboxylic acid compound having 1 to 20 carbon atoms according to the present invention had an average particle diameter of 24 to 25 μm and a coefficient of variation of 19% or less As shown in Fig. In addition, the polymer beads of Examples 1 to 12 exhibit an endothermic reaction at a high temperature of 190 to 240 캜 as a result of DSC analysis, and all of them are crystallized. Through the application of the internal crystallinity, the polymer beads of Examples 1 to 12 exhibited a weight loss of not more than 13.5% at a high temperature (after 250 ° C / 30 min heat treatment), a color difference Δb * value of not more than 10, It can be confirmed that the weight loss temperature is very high at 260 ° C or more.

In particular, as shown in Table 3, the polymer beads of Examples 1 to 12 exhibited no discoloration in the visual evaluation of the color change after heat treatment at a high temperature, and the L * value even after heat treatment at a high temperature The b * value was maintained at 3.65 to 12.06, and the? B * value was 2.29 to 9.2, so that the color change was minimized and excellent optical characteristics were maintained.

On the other hand, the polymer beads of Comparative Example 1 prepared without the separate carboxylic acid compound have similar physical properties such as average particle size, coefficient of variation, and crosslinking degree, but no endothermic peak at 200 ° C or higher is observed It can be seen that no crystallinity is imparted. In particular, the weight loss at high temperature is 47.97%, which is greater than 16%, which is significantly larger than that of the polymer beads of Examples 1 to 12, whereby the polymer beads of Comparative Examples 1 and 2 are subjected to a process of extrusion, It is confirmed that there are many problems to apply. In addition, as shown in Table 3, the polymer beads of Comparative Example 1 showed discoloration from the visual evaluation of the color change after the heat treatment at high temperature. In the evaluation using the colorimeter, the L * value was 74.52 after the heat treatment at a high temperature, The value of -2.54 and the b * value of 26.19, indicating that the color change occurs at a large difference from the initial value, and in particular, the? B * value is 25.27, And is not suitable for extrusion at high temperatures.

On the other hand, as shown in FIG. 4 and FIG. 5, the polymer beads of Example 1 retained excellent particle shape even after the high temperature treatment and there was no color change after the heat treatment at high temperature, , The polymer beads of Comparative Example 1 were found to have many pieces of broken and crumbly shaped particles, and a distinct yellow color change appeared after the heat treatment at a high temperature.

The polymer beads prepared according to the present invention have excellent optical properties and have improved thermal stability at high temperatures. Therefore, the polymer beads can minimize the color change even in a heat treatment process at a high temperature and reduce volatile substances It is possible to remarkably reduce the occurrence of fumes in the extruder and to have improved thermal stability without addition of a material such as a heat stabilizer or an antioxidant.

FIG. 1 is a graph showing the results of DSC analysis using the polymer beads prepared in Example 1 and Comparative Example 1. FIG.

FIG. 2 is a graph showing the results of TGA analysis using the polymer beads prepared in Example 1 and Comparative Example 1. FIG.

3 is a photograph showing FE-SEM measurement results after heat treatment in a crucible at 250 캜 for 30 minutes using the polymer bead prepared in Example 1. Fig.

4 is a photograph showing FE-SEM measurement results after heat treatment in a crucible at 250 캜 for 30 minutes using the polymer bead prepared in Comparative Example 1. Fig.

5 is a schematic diagram showing the CIE 1976-specified color coordinates used for evaluating the color change at high temperature for the polymer beads prepared in Examples 1 to 12 and Comparative Example 1.

6 is a photograph showing the result of color change measurement after heat treatment for 10 minutes, 20 minutes and 30 minutes in a crucible at 250 DEG C using the polymer beads prepared in Example 1. FIG.

7 is a photograph showing the result of color change measurement after heat treatment for 10 minutes, 20 minutes and 30 minutes in a crucible of 250 DEG C using the polymer beads prepared in Comparative Example 1. FIG.

Claims (10)

One or more monomers 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 fluoroalkyl methacrylate monomers having 1 to 20 carbon atoms; A carboxylic acid compound having 1 to 20 carbon atoms; A crosslinking agent; Initiator; And ion-exchanged water, The carboxylic acid compound is added in an amount of 1 to 15 parts by weight based on 100 parts by weight of the monomer, (DSC) analysis has at least one endothermic peak at 160 DEG C or higher, a 10 wt% reduction temperature at a thermogravimetric analysis (TGA) is 255 DEG C or higher, 250 DEG C for 30 minutes Wherein the weight loss after heat treatment is 15% or less and the? B * value according to the colorimeter measurement after heat treatment at 250 占 폚 for 30 minutes is 15 or less. The method according to claim 1, Wherein the monomer is selected from the group consisting of methyl methacrylate, styrene, divinyl benzene, butyl methacrylate, trimethylol methane tetraacrylate, trimethylol methane triacrylate, trimethylol butane triacrylate, and ethylene glycol dimethacrylate ≪ / RTI > The method according to claim 1, The carboxylic acid compound may be at least one selected from the group consisting of methacrylic acid, acetic acid, metaconic acid, citric acid, itaconic acid, acrylic acid, ascorbic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, phthalic acid, isophthalic acid, Wherein the polymer bead is at least one selected from the group consisting of maleic acid, maleic acid, and diphenyl ether dicarboxylic acid. The method according to claim 1, Wherein the carboxylic acid compound is added in an amount of 1.5 to 7 parts by weight based on 100 parts by weight of the monomer. The method according to claim 1, 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, diacrylate, polybutylene glycol diacrylate, allyl acrylate, 1,2-ethanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol dimethacrylate, Butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate re Diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol Wherein the polymer bead is at least one selected from the group consisting of dimethacrylate, polybutylene glycol dimethacrylate, allyl methacrylate, diallyl maleate, and trimethylolpropane triacrylate (TMPTA). The method according to claim 1, Wherein the initiator is selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, azobiscenyl butyronitrile, azobiscyclohexanecarbonitrile, potassium persulfate, sodium persulfate, ammonium persulfate, and azo based water- At least one polymer bead selected. The method according to claim 1, 100 parts by weight of at least one monomer 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, 1 to 15 parts by weight of a carboxylic acid compound having 1 to 20 carbon atoms, 1 to 98 parts by weight of a crosslinking agent, 1 to 5 parts by weight of initiator, and Ion-exchange water ≪ / RTI > The method according to claim 1, A polymer bead having an average particle diameter of 1 to 50 占 퐉 and a coefficient of variation (CV) of 30% or less. The method according to claim 1, A polymer bead having a weight change loss rate of 12% or less after heat treatment at 250 占 폚 for 30 minutes. The method according to claim 1, A polymer bead having a? B * value of 13 or less according to a colorimeter measurement after heat treatment at 250 占 폚 for 30 minutes.

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