KR20110032856A - Polymeric beads having a good thermal stability in the high temperature conditions - Google Patents

Abstract

PURPOSE: Polymeric beads are provided to minimize the generation of fume since physical and chemical changes are not caused even in high temperature treatment processes. CONSTITUTION: Polymeric beads are prepared by a composition consisting of: at least one monomer selected from the group consisting of aromatic vinyl monomer, C1~20 acrylic acid or methacrylic acid alkyl ester monomer, and C1~20 acrylic acid or methacrylic acid fluoroalkylester monomer; and C1~20 carboxylic acid compound; crosslinking agent; initiator; and ion exchange water. Polymeric beads have at least one endothermic peak at 160 °C or more in differential scanning calorimetry analysis and 10 weight% loss temperature of 255 °C or more in thermogravimetric analysis.

Description

Polymer beads with excellent thermal stability at high temperatures {POLYMERIC BEADS HAVING A GOOD THERMAL STABILITY IN THE HIGH TEMPERATURE CONDITIONS}

The present invention relates to polymer beads having enhanced heat resistance, and more particularly, to polymer beads having excellent thermal stability at high temperature with excellent optical properties.

The polymer particles collectively refer to spherical particles having a uniform particle size distribution produced by emulsion polymerization, suspension polymerization or the like. The use of polymer particles is so diverse that it is not only used for light diffusing films, protective films and constructions of liquid crystal monitors, but also widely used for coating transparent films for color inks.

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

In conventional suspension polymerization, the polymer particles are prepared by dispersing the monomer present in the aqueous solution by mechanical force. Polymer particles produced by this method have a particle size of at least 100 μm or more, and the particle distribution tends to be wide because the particles are dispersed by mechanical force. In this regard, US Pat. Nos. 4,017,670, 4,071,670, 4,085,169, 4,129,706, and the like introduce techniques for producing polystyrene polymer beads by suspension polymerization.

As such, the polymer particles prepared through the conventional polymerization process may provide a hiding power because the refractive index of the polymer is different from that of the conventional resin, and thus, the polymer particles are widely used when they are manufactured by extruding a light diffusion plate or a lighting fixture. In this way, when the product is made by extrusion, it is required to mix the product at a high temperature so that excellent thermal stability is required. However, when the conventional polymer beads are suspended for 30 minutes or more at a high temperature, the weight change reduction width is large and may cause physical and chemical changes in the environment in which the beads are used. That is, the physical properties of the final product may be reduced due to the decrease in compatibility, the generation of fume or by-products, and the change in physical properties such as the shape of the particles is severely deformed when the SEM image is read.

Therefore, even when the high temperature heat treatment step is performed in the manufacturing process when applied to various uses such as a light diffusion film, color change and fume generation are minimized, and there is no change in physical properties. There is a need for research on the development of stable polymer beads.

The present invention seeks to provide polymer beads imparted with excellent optical properties and heat resistance at the same time.

The present invention is an aromatic vinyl monomer, at least one monomer selected from the group consisting of acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, and acrylic acid or methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms; Carboxylic acid compounds having 1 to 20 carbon atoms; Crosslinking agents; Initiator; And ion-exchanged water, having one or more endothermic peaks at 160 ° C. or higher in differential scanning calorimetry (DSC) analysis, and losing 10% by weight in thermogravimetric analysis (TGA). Polymer beads having a temperature of at least 255 ° C are provided.

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

In the preparation of the polymer beads, the present inventors have endeavored to impart improved thermal stability at high temperature with excellent optical properties, and include a predetermined carboxylic acid compound, a crosslinking agent, an initiator, and ion-exchanged water together with a predetermined monomer. The polymer beads are prepared using the composition, and have excellent optical properties and heat resistance by having a physical property measurement value over a predetermined range in differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). It has been found that polymer beads having can be prepared.

In particular, in the present invention, by adding a predetermined carboxylic acid compound with a crosslinking agent, an initiator, and the like in the process of producing a polymer bead having excellent optical properties using a predetermined monomer, as well as increasing the bond in the polymer chain direction according to the polymerization reaction It is possible to increase the binding force between the polymer chain and the chain and thereby impart crystallinity, so that polymer beads having improved thermal stability at high temperature with excellent optical properties can be produced.

The internal crystalline polymer beads of the present invention basically refers to beads consisting of polymethyl methacrylate beads, polystyrene beads, polyurethane beads, etc. Among them, polymethacrylate beads and the like are more preferable in terms of optical properties. Can be.

Accordingly, according to an embodiment of the present invention, the present invention is prepared from a composition having a predetermined composition, and measured in a differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) to measure properties over a predetermined range. Polymer beads having values are provided. Such polymer beads may include at least one monomer selected from the group consisting of aromatic vinyl monomers, acrylic acid or methacrylic acid alkylester monomers having 1 to 20 carbon atoms, and acrylic acid or methacrylic acid fluoroalkyl ester monomers having 1 to 20 carbon atoms; Carboxylic acid compounds having 1 to 20 carbon atoms; Crosslinking agents; Initiator; And ion-exchanged water, having one or more endothermic peaks at 160 ° C. or higher in differential scanning calorimetry (DSC) analysis, and losing 10% by weight in thermogravimetric analysis (TGA). The temperature may be higher than 255 ° C.

In particular, the polymer beads of the present invention may have one or more endothermic peaks at 160 ° C. or higher or 160 to 300 ° C., preferably 180 ° C. or higher or 180 to 250 ° C. in differential scanning calorimeter (DSC) analysis. Can be. In the case of differential scanning calorimeter (DSC) analysis, when one or more endothermic peaks do not appear at 160 ° C. or higher, internal crystallinity is not imparted to the polymer beads, resulting in poor thermal stability and high optical properties. Can't keep up

The polymer beads of the present invention have one or more endothermic peaks at 160 ° C. or higher in differential scanning calorimeter (DSC) analysis, thereby imparting internal crystallinity and improving thermal stability at high temperature with excellent optical properties. Can be. In particular, the polymer bead may have an endothermic peak at a high temperature of 160 ° C. or higher in the first scan, but no endothermic peak may be observed in the second scan. This is because the endothermic peaks in the beads of the present invention are not related to polymer chain-forming bonds, but to bond forms that may appear between polymer chains, that is, such as hydrogen defects. It can be seen that.

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

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

In this case, the monomer is one or more selected from an aromatic vinyl monomer, acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms and acrylic acid or methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms. For example, methyl methacrylate (methylmethacrylate), styrene, divinyl benzene, butyl methacrylate (butylmethacrylate), trimethylolmethane tetraacrylate, trimethylolmethane Trimethyl acrylate (trimethylolmethane triacrylate), trimethylolbutane triacrylate (trimethylolbutane triacrylate), ethylene glycol dimethacrylate (ethylene glycol dimethacrylate) and the like can be used. Among the monomers, methyl methacrylate, styrene, divinylbenzene, butyl methacrylate, and the like are preferable in terms of securing excellent optical properties of the polymer beads.

The content of the monomer may be included in 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% by weight or more in terms of particle size control, and may be 50% by weight or less in terms of increasing the degree of crosslinking. The content of such monomers 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 final polymer beads.

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

The carboxylic acid compound may be included in an amount of 1 to 15 parts by weight, preferably 1.5 to 7 parts by weight, and 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 terms of imparting internal crystallinity, and may be 15 parts by weight or less in terms of polymerization stability. At this time, the content of the carboxylic acid compound is preferably to maintain the content of the additive viscosity so that the polymer beads of excellent optical properties from the monomer, and when added in excess of the content range is polymerized as an additional monomer Participation in the reaction may result, making it difficult to prepare polymer beads with the desired good optical properties. The content of such 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 final polymer beads.

In addition, the crosslinking agent is 1,2-ethanediol diacrylate, 1,3-propanedioldiacrylate, 1,3-butanedioldiacrylate, 1,4-butanedioldiacrylate, 1,5-pentanedioldi 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, 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 Relate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol methacrylate, polyethylene glycol dimethacrylate, polypropylene One or more selected from the group consisting of glycol dimethacrylate, polybutylene glycol dimethacrylate, allyl methacrylate, diallyl maleate, and trimethylolpropane triacrylate (TMPTA) may be used. . Among them, 1,2-ethanediol diacrylate, ethylene glycol diacrylate, triethylene glycol diacrylate, and the like are more preferable in terms of imparting polymerization stability.

The crosslinking agent may be included in an amount of 1 to 98 parts by weight, preferably 5 to 50 parts by weight, and 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 terms of solvent resistance enhancement, and may be 98 parts by weight or less in terms of polymerization yield. The content of such a 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 the final polymer beads.

The initiator is a group consisting of benzoyl peroxide, azobisisobutyronitrile, azobiskenylbutyronitrile, azobiscyclohexanecarbonitrile, potassium persulfate, sodium persulfate, ammonium persulfate and azo water-soluble initiator and peroxide Peroxide-based compounds such as benzoyl peroxide, lauryl peroxide, octanoyl peroxide, and dicumyl peroxide may be selected and used. Among them, from the viewpoint of polymerization stability, benzoyl peroxide, azobisisobutyronitrile, azobiskenylbutyronitrile and the like are more preferable.

It is preferable to use the said polymerization initiator in the range of 1-5 weight part with respect to 100 weight part of total monomers. At this time, if the content thereof is less than 1 part by weight, there is a problem that an unreacted monomer is excessively generated, and if it exceeds 5 parts by weight, there is a problem that polymerization stability is poor due to rapid exotherm.

In addition, the composition for preparing the polymer beads may further add a dispersion stabilizer for suspension stabilization. In this case, as the dispersion stabilizer, polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, sodium carboxymethyl cellulose, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, sodium polymethacrylate, gelatin, One or a mixture of two or more selected from the group consisting of polyacrylamide, polyethylene oxide, polyvinyl methyl ether, polyethyleneimide, vinyl acetate copolymer, hydroxypropyl cellulose, silica and siloxane can be used. In particular, polyvinyl alcohol, polyvinyl methyl ether, vinyl acetate copolymer, and the like are more preferable in terms of polymerization stability.

The dispersion stabilizer may be included in an amount of 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 such dispersion stabilizer is less than 1 part by weight, the emulsion stability is poor, and there is a problem that a large amount of polymer aggregates are generated. If the content is more than 50 parts by weight, it is difficult to remove the dispersion stabilizer in the washing process of the polymer beads. .

In addition, the composition includes ion exchanged water together with monomers, carboxylic acid compounds, crosslinking agents, initiators and the like. The ion exchange water used in the present invention is preferably less cation, more preferably 5 MΩ or more of ultrapure water under a nitrogen stream generated through the ion exchange group. In this case, the ion-exchanged water may be added to the total composition except the sum of the content including the monomer, the carboxylic acid compound, the crosslinking agent, the initiator, etc., preferably the composition is polymer beads through suspension polymerization It may be added to adjust the content to a degree suitable for performing the process.

On the other hand, in view of simultaneously securing excellent optical properties and thermal stability at high temperatures of the polymer beads of the present invention, the composition is an aromatic vinyl monomer, acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, and carbon atoms 1 to 100 parts by weight of at least one monomer selected from the group consisting of 20 acrylic or methacrylic acid fluoroalkyl ester 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, initiator 1 To 5 parts by weight, and ion-exchanged water.

In addition, the polymer bead composition is 1 selected from the group consisting of an aromatic vinyl monomer, acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms, and acrylic acid or methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms. 100 parts by weight or more of 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, 1 to 5 parts by weight of an initiator, 1 to 50 parts by weight of a dispersion stabilizer, and ion exchanged water. It may be.

The polymer beads of the present invention are prepared using the composition, and in particular, aromatic vinyl monomers, acrylic acid or methacrylic acid alkylester monomers having 1 to 20 carbon atoms, and fluoroalkyl esters having acrylic acid or methacrylic acids having 1 to 20 carbon atoms. It may be prepared by a method comprising the 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-exchanged water.

In a more preferred embodiment, the present invention can prepare a polymer bead by preparing a monomer solution comprising a monomer and an initiator and then suspending it in an aqueous system to polymerize. At this time, in the preparation of the monomer solution, the crystallinity is imparted to the inside to impart hydrogen bonds to the inside, thereby making it possible to manufacture polymer beads having enhanced heat resistance than the existing spherical polymer beads. In particular, the present invention provides crystallinity by adding a carboxylic acid compound in the step of preparing spherical polymer beads by suspension polymerization, for example, the crosslinking degree is 1% to 98%, the average particle diameter is 1㎛ to 50㎛ Coefficient of variation (CV) has a very uniform particle distribution of 30% or less, has an endothermic peak at 160 ° C. or higher due to internal crystallization, etc., and a 10% by weight reduction temperature of 255 ° C. or more. It is possible to produce polymer beads to which thermal stability is imparted without substantially changing the shape of the beads or reducing the weight change even when the particles are held for 30 minutes or more at a high temperature of 250 ° C. or higher.

In preparing the polymer beads of the present invention, the suspension is mixed with a monomer, a carboxylic acid compound, a crosslinking agent, an initiator, and ion-exchanged water, and the stirring speed is 100 to 600 rpm, preferably 200 to 500 rpm, more preferably. It may be prepared by performing the step of stirring at 250 to 300 rpm. In addition, the suspension is further carried out by mixing the monomer, carboxylic acid compound, crosslinking agent, initiator, and ion-exchanged water and stirring at high speed at a homomixer at 1,000 to 6,000 rpm, more preferably 2,000 to 4,000 rpm. It may be to be prepared. At this time, in the preparation of the suspension, even if the stirring is not sufficiently high speed, even if using a homo mixer may be stable and the desired particle formation may not be achieved. In addition, agglomeration may occur when the suspension is polymerized immediately after high-speed agitation. By using a homomixer with sufficient agitation as described above, such agglomeration can be effectively prevented, and a particle distribution of 100 μm or more can be obtained. It is possible to minimize the production of very wide polymer beads.

In addition, the step of polymerizing the suspension may be carried out under the conditions of the reaction temperature 60 ℃ to 90 ℃, under a stirring speed of 100 to 600 rpm, preferably 200 to 500 rpm, more preferably 250 to 300 rpm Can be done.

As described above, the polymer beads in which the polymerization reaction is completed are separated by filtration, washed three to four times using ion-exchanged water, dehydrated, and vacuum dried at 70 ° C. for 24 hours to obtain final polymer beads. In some cases, for example, when the particles are agglomerated during drying, it is preferable to perform the grinding step with a grinder such as a jet mill, a ball mill atomizer or a hammer mill.

In the present invention, by adding the carboxylic acid compound to impart crystallinity in the step of preparing the spherical polymer beads by suspension polymerization, it is possible to prepare polymer beads having excellent optical properties and improved thermal stability at high temperature.

Meanwhile, the polymer beads of the present invention have an average particle diameter of 1 μm to 50 μm, preferably 1 μm to 40 μm, more preferably 5 μm to 30 μm, and a coefficient of variation (CV) of 30% or less. Or 5% to 30%, preferably 25% or less, more preferably 20% or less. Polymer beads having such particle size and coefficient of variation can ensure excellent optical properties in terms of film processing stability, and thus can be effectively used for LCD backlight material.

The polymer beads may have a crosslinking degree of 1% to 98%, preferably 1% to 50%. Although the degree of crosslinking is largely dependent on the crosslinking agent, in the case of the present invention, the degree of internal crystallinity due to the bond between the polymer chains and the chains can also be improved, and thus the degree of crosslinking can be obtained. Thermal stability can be secured.

The polymer beads may have a weight loss reduction rate of 15% or less, preferably 12% or less, and more preferably 5% or less after heat treatment at 250 ° C. for 30 minutes, which is about 40% of conventional polymer beads. It can be seen that it has a significantly improved thermal stability compared to the weight change reduced in excess.

In addition, the polymer beads after heat treatment at 250 ° C. for 30 minutes may have a Δb * value of 15 or less or 0 to 15, preferably 13 or less, more preferably 10 or less. At this time, the ΔL * value after the heat treatment may be -20 to 0, preferably -17 to 0, more preferably -15 to 0, the △ a * value after the heat treatment may not have a large difference However, the absolute value of the Δa * value may be preferably 2.0 or less or 2.0 to 0, more preferably 1.5 or less. In view of the Δb * value, ΔL * value, and Δa * value to exhibit excellent optical properties when applied to a diffuser plate or a diffusion film on a backlight unit (BLU) for optical display applications, Δ b * It may be more important to minimize the value and prevent yellowing. In particular, the polymer beads of the present invention having such a minimized color change value can secure excellent optical properties in terms of film processing stability, and can obtain excellent effects in preventing yellowing during extrusion.

On the other hand, the present invention, as described above, can provide a molded article produced using the polymer beads effectively imparted internal crystallinity, which includes a film, extrusion, injection, casting molding. That is, the polymer beads imparted with internal crystallinity of the present invention may be used as a light diffusing agent for a light diffusing film and a light diffusing plate of a backlight unit (BLU) in the field of display materials, and as a light diffusing agent for an illuminating back cover. Preferably, since the polymer beads imparted with internal crystallinity of the present invention have better heat resistance than the existing beads, the polymer beads may be used as a light diffusing agent for a light diffusion plate or an illumination cover for extrusion or injection.

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 is prepared using a composition comprising a monomer, a carboxylic acid compound, a crosslinking agent, an initiator, and ion-exchanged water in a predetermined composition, and differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) By having a property value within a predetermined range in Analysis), the polymer beads themselves can be internally crystallized, thereby providing excellent optical properties such as refractive index, minimizing color change at high temperatures, and effectively producing polymer beads having improved thermal stability. .

The polymer beads manufactured according to the present invention have substantially no physical or chemical change even at a high temperature heat treatment process, so that there is no or minimal fume generation, which is a problem when manufacturing various products such as electronic parts, thereby minimizing the final product. It is possible to effectively exhibit the excellent physical properties required for the beads without adversely affecting the physical and chemical properties.

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 Table 1 below, 100 parts by weight (386.6 g) of methyl methacrylate (methylmethacrylate, MMA), 12 parts by weight (46.4 g) of ethylene glycol dimethacrylate (EGDMMA), and azobisisobutyro 1 part by weight of nitrile (azobisisobutyronitrile (ABIBN) (3.8 g), 3 parts by weight of methacrylic acid (MAA) (11.6 g), and ion-exchanged water (918.13 g) were mixed to prepare a suspension, The mixture was stirred at 700 rpm for 30 minutes. The suspension was discharged from the reactor and subjected to vigorous stirring by repeating twice at 4,000 rpm in a homomixer. The suspension was added again to a 2 L reactor and heated at an internal temperature of 60 ° C. while stirring at 250 rpm under a nitrogen stream, and then reacted at 60 ° C. for 7 hours, followed by filtration, washing, dehydration and drying. 386 g of polymer beads were prepared.

Example  2 ~ 4

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

Example  5 ~ 8

As shown in Table 1, instead of methacrylic acid (methacrilic acid, MAA), instead of methaconic acid (methaconic acid, MCA), acetic acid (acetic acid, AcA), acrylic acid (acrylic acid, AA), ascorbic acid (ascorbic acid) 280 g of polymer beads were prepared in the same manner as in Example 1, except that AsA) was used.

Example  9 ~ 11

As shown in Table 1 below, styrene, trimethylolpropane triacrylate (TMPTA), benzoyl peroxide (BZPO), polyvinyl alcohol (polyvinylalcohol) with different monomers, crosslinking agents and initiators, respectively 300 g of polymer beads were prepared in the same manner as in Example 1, except that PVA) was used.

Example  12

As shown in Table 1, 354 g of polymer beads in the same manner as in Example 1, except that polyvinyl alcohol was further added to 6 parts by weight based on 100 parts by weight of the monomer as a dispersion stabilizer, followed by mixing. Was prepared.

Comparative example  One

As shown in Table 1, 380 g of polymer beads were prepared in the same manner as in Example 1, except that no methacrylic acid was added.

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

division Monomer Carboxylic acid Crosslinking 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 physical 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 coefficient of variation (C.V.): Coefficient of variation )

The average particle diameter of the polymer beads was measured using a particle size distribution measuring device (C.V .: Coefficient of Variation) (Colter Electronics, Inc., Multisizer 3), and the coefficient of variation (C.V.) was calculated by the following equation.

[Calculation 1]

C.V. (%) = (Standard deviation of particle size / average particle diameter) × 100

b) crystallinity assessment

The crystallinity evaluation of the polymer beads was measured by differential scanning calorimeter (DSC) analysis, which can be determined by viewing the thermal changes of the beads using a DSC analyzer. In particular, it can be seen that there is an endothermic reaction at high temperature (160 ° C. or higher) when crystallinity is given to the inside during DSC analysis, so that internal bonds exist. In this case, when the internal crystallinity is given, an endothermic peak is found at a high temperature (160 ° C or higher) in the first scan, but the endothermic peak is not observed in the second scan.

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

In addition, the graphs of the DSC analysis results of the polymer beads prepared in Example 1 and Comparative Example 1 are shown in FIG. 1.

c) weight change at elevated temperatures Loss ratio  evaluation

Evaluation of the weight loss loss rate at high temperature for the polymer beads was measured by the thermogravimetric analysis, and the heat loss weight analysis was put in a crucible 8 g each of the polymer beads in a 250 ℃ oven after standing for 30 minutes to measure the weight loss, It computed as shown in following formula 2.

[Equation 2]

d) TGA  evaluation

TGA was measured on the polymer beads to confirm the temperature at the 10% weight loss point. In particular, the TGA measurement was performed under air conditions, after heating at 30 ° C. to 250 ° C., stopping heating at 250 ° C. for 10 minutes, heating at 250 ° C. to 600 ° C., and stopping the heating at 250 ° C. in the extruder during extrusion. Assuming stagnant time. A graph of the TGA measurement results is shown in FIG. 2, and the point at which the weight of the polymer beads is reduced by 10% is shown in Table 2 below.

e) high temperature After treatment SEM  Measure

The polymer beads of Example 1 and Comparative Example 1 were placed in a crucible, respectively, and allowed to stand in a 250 ° C. oven for 30 minutes, followed by FE-SEM measurements, which are shown in FIGS. 3 and 4, respectively.

division Average particle diameter
(Μm) CV
(%) High temperature endothermic peak
(℃) Weight loss rate
(After 250 ℃ / 30min heat treatment,%) 10% weight loss
(℃) 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

In addition, the color change evaluation at high temperature was performed using the color change evaluation and the color difference meter according to the visual evaluation of the polymer beads prepared according to Examples 1 to 12 and Comparative Example 1. At this time, color change evaluation at high temperature was placed in a crucible of 8 g of polymer beads in a 250 ° C. oven for 30 minutes, and then color change was measured by visual evaluation and JISZ 8729 method using a color difference meter (NIPPON DENSHOKU SD5000). .

As shown in FIG. 5, in the color coordinates of the CIE 1976 standard according to the L * a * b * expression method, L * is an index defining brightness, white toward 100, black toward 0, and a * indicates red and green. If you go to +, RED, go to Green, b * is Yellow and Blue, and if you go to Yellow,-go Blue. Among them, the yellowing index (Yellow index) of the polymer beads was determined by the change in the b * value (Δb * value).

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

division L * a * b * Δb * 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 a carboxylic acid compound having 1 to 20 carbon atoms according to the present invention have an average particle diameter of 24 to 25 µm and a coefficient of variation of 19% or less. It can be seen that it has very excellent characteristics. In addition, the polymer beads of Examples 1 to 12 show an endothermic reaction at a high temperature of 190 to 240 ° C. as a result of DSC analysis, and all of them have been given crystallinity. Through imparting such internal crystallinity, the polymer beads of Examples 1 to 12 had a weight loss of only 13.5% or less at a high temperature (after 250 ° C / 30min heat treatment), and a color difference Δb * value of 10 or less, 10% It can be seen that the weight loss temperature is very high, above 260 ° C.

In particular, as shown in Table 3, the polymer beads of Examples 1 to 12 had no discoloration in the visual evaluation of the color change after heat treatment at high temperature, and the L * value was increased even after heat treatment at high temperature in the evaluation using a color difference meter. 87.02 to 96.25, the a * value was maintained at -0.13 to -1.34, the b * value was 3.65 to 12.06, and the Δb * value was 2.29 to 9.2, thereby minimizing the color change, thereby maintaining excellent optical properties.

On the other hand, the polymer beads of Comparative Example 1 prepared without a separate carboxylic acid compound have similar physical properties such as average particle diameter, coefficient of variation, degree of crosslinking, but an endothermic peak at 200 ° C. or higher is not observed. It can be seen that no crystallinity is imparted. In particular, the weight loss at a high temperature is 47.97%, which is more than 16%, showing a significant change compared to the polymer beads of Examples 1 to 12, whereby the polymer beads of Comparative Examples 1 and 2 are subjected to heat such as extrusion and injection. Many problems have been found to apply. In addition, as shown in Table 3, the polymer beads of Comparative Example 1 were discolored from visual evaluation of color change after heat treatment at high temperature, and L * value was 74.52, a * after heat treatment at high temperature in evaluation using color difference meter. The value of -2.54 and the value of b * is 26.19, indicating that the color change occurs with a large difference from the initial value. Especially, the value of Δb * becomes 25.27, which is a significant color change compared to the polymer beads of Examples 1 to 12. It appears that it is not suitable for use for extrusion at high temperatures.

On the other hand, as shown in Figures 4 and 5, while the polymer beads of Example 1 maintain the excellent particle shape even after a high temperature treatment and there is no separate color change even after heat treatment at a high temperature, as shown in Figure 6 and 7 The polymer beads of Comparative Example 1 were found to have many fragmented and broken particles, and a clear yellow color change after heat treatment at high temperature.

As described above, the polymer bead prepared according to the present invention has excellent optical properties and improved thermal stability at high temperature, and can minimize color change even in the heat treatment process at a high temperature, and volatilizes materials due to internal crystallinity. Therefore, it is possible to significantly reduce the generation of fume (fume) in the extruder, and also it can be seen that it has improved thermal stability without adding a material such as a separate heat stabilizer or antioxidant.

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

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

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

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

Figure 5 is a schematic diagram showing the color coordinates of the CIE 1976 standard used for the color change evaluation at high temperatures for the polymer beads prepared in Examples 1-12 and Comparative Example 1.

Figure 6 is a photograph showing the color change measurement results after heat treatment for 10 minutes, 20 minutes, 30 minutes in a crucible at 250 ℃ using the polymer beads prepared in Example 1.

7 is a photograph showing the color change measurement results after heat treatment for 10 minutes, 20 minutes, 30 minutes in a crucible at 250 ℃ using the polymer beads prepared in Comparative Example 1.

Claims (10)

At least one 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 methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms; Carboxylic acid compounds having 1 to 20 carbon atoms; Crosslinking agents; Initiator; And ion exchanged water, Polymer beads having at least one endothermic peak at 160 ° C. or higher in differential scanning calorimetry (DSC) analysis, and having a 10 wt% weight loss temperature of at least 255 ° C. in thermogravimetric analysis (TGA). The method of claim 1, The monomer is a group consisting of methyl methacrylate, styrene, divinylbenzene, butyl methacrylate, trimethylolmethane tetraacrylate, trimethylolmethane triacrylate, trimethylolbutane triacrylate, and ethylene glycol dimethacrylate. At least one polymer bead selected from. The method of claim 1, The carboxylic acid compound is methacrylic acid, acetic acid, metaconic acid, citric acid, itaconic acid, acrylic acid, ascorbic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azeline acid, phthalic acid, isophthalic acid, naphthalene dicarboxylic acid At least one polymer bead selected from the group consisting of main acid, and diphenyl ether dicarboxylic acid. The method of claim 1, The carboxylic acid compound is a polymer bead added in 1 to 15 parts by weight based on 100 parts by weight of the monomer. The method of claim 1, The crosslinking agent is 1,2-ethanedioldiacrylate, 1,3-propanedioldiacrylate, 1,3-butanedioldiacrylate, 1,4-butanedioldiacrylate, 1,5-pentanedioldiacrylate 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 dimethacryl re , Triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol At least one polymer bead selected from the group consisting of dimethacrylate, polybutylene glycol dimethacrylate, allyl methacrylate, diallyl maleate, and trimethylolpropane triacrylate (TMPTA). The method of claim 1, The initiator is selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, azobiskenylbutyronitrile, azobiscyclohexanecarbonitrile, potassium persulfate, sodium persulfate, ammonium persulfate, and an azo water-soluble initiator. At least one polymer bead selected. The method of claim 1, 100 parts by weight of at least one 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 methacrylic acid fluoroalkyl ester monomer 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 crosslinking agent, 1 to 5 parts by weight of initiator, and Ion exchange water Polymer beads made of a composition comprising a. The method of claim 1, Polymer beads having an average particle diameter of 1 to 50 µm and a coefficient of variation (C.V.) of 30% or less. The method of claim 1, Polymer beads having a weight loss reduction rate of 15% or less after heat treatment at 250 ° C. for 30 minutes. The method of claim 1, Polymer beads whose Δb * value is 15 or less according to the colorimeter measurement after heat treatment at 250 ° C. for 30 minutes.

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