KR100521144B1 - Living Radical Initiator for polymerization and Method for manufacturing polymethylmethacrylate powder using thereof - Google Patents

Abstract

The present invention relates to a living radical initiator for polymer polymerization and a method for preparing PMMA (polymethylmethacrylate) powder using the same.

The novel living radical initiator for polymer polymerization according to the present invention is 2,8-dithiocarbamoyl sulfanyl-4-piperazine-1,10-dimethylbenzoic acid (2,8-dithiocarbamoyl sulfanyl-4-piperazine-1,10 -dimethylbenzoic acid), the polymethyl methacrylate powder production method according to the present invention is carried out by the emulsion polymerization method or suspension polymerization method using the above-mentioned living radical initiator and the light of 250 ~ 380nm wavelength,

According to the production method using the initiator of the present invention, the polymethyl methacrylate powder having a uniform particle size distribution can be produced simply and effectively, and the particle size of the desired size is controlled by controlling the particle size only by controlling the initiator content. It can be easily obtained, and the reaction time can be shortened by two to three times compared with the conventional nitroxide method or RAFT method, and complicated and difficult process such as separating transition metal in polymer purification process as in ATRP method. There is no advantage at all.

Description

Living Radial Initiator for Polymer Polymerization and Manufacturing Method of PMMA Powder Using the Same {Living Radical Initiator for polymerization and Method for manufacturing polymethylmethacrylate powder using

The present invention relates to a living radical initiator for polymer polymerization and a method for producing PMMA powder using the same, and more particularly, to a uniform particle size by a novel initiator for polymer polymerization containing an emulsifier component and a living radical polymerization method using the same. A method for producing a polymethyl methacrylate powder having a distribution.

Conventionally, as an example of a method for producing polymethylmethacrylate powder, a method of preparing a stabilizer in a slurry state, preparing an auxiliary stabilizer dispersion, and using an azo compound as an initiator has been proposed in Korean Patent Publication No. 2001-94318. A method of using an azo-based and peroxide initiator to selectively control the characteristic elements of a polymer has been proposed in Korean Patent Publication No. 2002-3403, but it is still not easy to obtain a powder of uniform size by the above-described polymerization method. There is a problem.

In general, heterogeneous polymerization, such as emulsion polymerization or suspension polymerization, is one of the important methods of polymer synthesis, but has many advantages over homogeneous polymerization, but since all radicals do not start at the same time and the termination reaction is predominant, It is difficult to control and difficult to obtain a polymer of uniform size.

To compensate for these drawbacks, the iniferter method, the nitroxide method, the atom transfer radical polymerization (ATRP) method using Cu or Co, dithioesters or trithiocarbonates, etc. Living radical methods, such as the reversible addition-fragmentation chain transfer (RAFT) method, have been attracting industrial attention.

However, the Iniferter method has a disadvantage in that the exchange rate between the active species and the dormant species is slow compared to the growth reaction rate, so that the molecular weight distribution is very wide and the molecular weight is difficult to control. The method has a disadvantage in that the reaction takes too long, and the ATRP method has a disadvantage in that it is difficult to separate the transition metal during the polymer purification process.

Therefore, the present inventors have been studying for many years to improve the problems of the conventional methods described above, and as a result, the interaction between the additives by providing a variety of functions to one initiator to be effectively used in heterogeneous polymerization A novel initiator containing an emulsifier component has been synthesized to reduce the molecular weight and to facilitate molecular weight adjustment, thereby completing the present invention.

A first object of the present invention is to provide a novel living radical initiator for polymer polymerization, which can easily and effectively obtain polymer particles having a uniform particle size distribution.

The second object of the present invention is a polymethylmeta which is simple and effective in the production process by the UV irradiation of the wavelength of 250 ~ 380nm using a novel initiator according to the first object of the present invention and the selective control of the reactants It is to provide a production method by a living radical polymerization method of acrylate powder.

Hereinafter, the present invention will be described in detail.

The novel living radical initiator for polymer polymerization according to the present invention is represented by the following structural formula (I).

[Formula I]

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2,8-dithiocarbamoyl sulfanyl-4-piperazine-1,10-dimethylbenzoic acid (2,8-dithiocarbamoyl sulfanyl-4-piperazine-1,10-dimethylbenzoic acid)

More specifically, the initiator represented by the structural formula (I) according to the present invention, 4-diethylthiocarbamoyl sulfanyl methyl benzoic acid (DTBA) represented by the following structural formula (II) The 254 nm or 356 nm wavelength light source reversibly decomposes the active 4-methylbenzoic acid radical and the dormant diethyldithiocarbamoyl radical, and the 4-methylbenzoic acid radical is a monomer methylmethyl. Reaction with methacrylate (MMA) causes living polymerization to increase molecular weight, and the growing radical reacts with dormant species and terminates again. Can occur, and the molecular weight of the final product, polymethyl methacrylate, can be easily controlled.

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Scheme 1

In the polymerization method according to the present invention using the initiator represented by Structural Formula (I) according to the present invention, it is preferable to use an emulsion polymerization having a low dispersion degree of particles in a heterogeneous system, and the component of the emulsifier to the initiator without using an emulsifier separately. By reducing the interaction between the additives that can occur in the heterogeneous system, it is possible to control the particle size more easily by reducing the variable of the molecular weight. More specifically, the initiator represented by the above-mentioned structural formula (I) used in the present invention contains a hydrophilic functional group that acts as an emulsifier, and when the amount of the initiator is increased, the critical micelle concentration is higher than the critical micelle concentration. It is characteristic that particles always produce the same size even in concentration.

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In addition, the initiation reaction in the production method according to the present invention may be any of heat, light or radiation, but the initiator used in the present invention is characterized by generating radicals by irradiation of ultraviolet rays, so it is preferable to use light. Preferably, the ultraviolet rays A to C region may be used. In more detail, it is preferable to selectively use ultraviolet rays of 254 nm or 365 nm.

In addition, as the polymer polymerization method used in the preparation method of the present invention, an emulsion or suspension polymerization method may be used. Preferably, by using emulsion polymerization, polymerized particles having the same size may be more effectively obtained, and monomers may be obtained. Additional additions do not produce new particles and continue to grow evenly in particle size. In addition, when the stirring speed is lower during the polymerization reaction, the size of the particles increases, but when the stirring speed is 200 rpm or less, there is a fear that aggregation may occur. On the other hand, when the stirring speed is too high, the particles may be broken.

In the production method of the present invention, the particle size and distribution control of the polymethyl methacrylate powder to be prepared can be carried out by appropriately adjusting the UV irradiation time, the amount of the initiator, the content of solids as necessary, Since a person skilled in the art can be easily selected by appropriate selection, specific description thereof will be omitted.

In addition, the production method of the present invention may use a conventional reactor or a water jacket reactor, more preferably using a quartz reactor.

Hereinafter, the present invention will be described in more detail through Examples, Reference Examples and Comparative Examples. Reference Example 1: Synthesis of Initiator of Structural Formula (II) Sodium diethyldithiocarbamate trihydrate (225.31 g / mol) and (alpha) -bromo-p-toluic acid (215.05 g / mol) was dissolved in methanol, and bromination was carried out while injecting nitrogen gas at a temperature of about 80 ° C for about 30 minutes.

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The solvent is removed through fractional distillation, the obtained reactant is washed with distilled water to remove impurities, dissolved in sodium hydroxide aqueous solution to remove impurities, precipitated with aqueous hydrogen chloride solution, washed with distilled water and dried under vacuum to give a white yellow target substance. Got.

This is shown in Scheme 2 below.

Scheme 2

Example 1 Synthesis of Initiator of Structural Formula (I) 86.14 g of 1 mol of piperazine was charged into a 2 liter reactor, diluted with 1 liter of chloroform, and the temperature inside the reactor was maintained at 0-10 ° C. 152 g of 2 mol of carbon disulfide was slowly added into the reactor and stirred for 1 hour.

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Chloroform used as a diluting solvent in the reactor was removed under reduced pressure, and 40 g of sodium hydroxide was dissolved in 100 ml of distilled water, and added at room temperature, followed by stirring for 1 hour. 2 mol of 4- (bromomethyl) benzoic acid was dissolved in 800 ml of methanol while maintaining the temperature inside the reactor at 80 ° C., and then reacted with stirring for 8 hours.

After the reaction, the solvent methanol was removed under reduced pressure to obtain a slightly yellow target substance.

This is shown in Scheme 3 below.

Scheme 3

Reference Examples 2-7 and Examples 2-7 and Comparative Examples 1-6: Preparation of Polymethylmethacrylate Powders The mixtures as shown in Table 1 below were prepared, respectively, and charged into a 2-liter quartz reactor and Each initiator as shown in Table 1 was administered inside the reactor (in Reference Example 1 and Example 1, it was administered in an aqueous solution dissolved in 5% aqueous sodium hydroxide solution).

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Subsequently, nitrogen gas was injected into the reactor while maintaining the reactor temperature at 25 ° C. The UV lamp (100w, 254nm) at a distance of 25cm away from the reactor was constantly stirred at 600rpm while irradiating for 6 hours.

Polymethyl methacrylate, a milky suspension after polymerization, was obtained through a freeze-drying process.

The particle size ranges of the obtained PMMA particles are also shown in Table 1 below.

Raw Material Content and Particle Size Range of Polymethylmethacrylate Powder Initiator 1 Initiator 2 Initiator 3 Crosslinking agent Monomer Distilled water Solid content Particle size Reference Example 2 1.02 g - - 5.95 g 53.55 g 290.5 g 17% 1-2㎛ Example 2 - 2.45 g - 5.95 g 53.55 g 290.5 g 17% 2-4㎛ Comparative Example 1 - - 0.97 g 5.95 g 53.55 g 290.5 g 17% 120-150nm Reference Example 3 0.51 g - - 5.95 g 53.55 g 290.5 g 17% 2-3㎛ Example 3 - 1.23 g - 5.95 g 53.55 g 290.5 g 17% 3-5㎛ Comparative Example 2 - - 0.49 g 5.95 g 53.55 g 290.5 g 17% 180-192 nm Reference Example 4 0.23 g - - 5.95 g 53.55 g 290.5 g 17% 4-6㎛ Example 4 - 0.61 g - 5.95 g 53.55 g 300 g 17% 5-6㎛ Comparative Example 3 - - 0.24 g 5 g 53.55 g 290.5 g 17% 200-215 nm Reference Example 5 0.23 g - - 8.25 g 73.25 g 268.5g 25% 10-12㎛ Example 5 - 0.61 g - 8.25 g 73.25 g 268.5g 25% 13-20㎛ Comparative Example 4 - - 0.24 g 8.25 g 73.25 g 268.5g 25% 18-24㎛ Reference Example 6 0.23 g - - 7 g 63 g 280 g 20% 5-8㎛ Example 6 - 0.61 g - 7 g 63 g 280 g 20% 8-10㎛ Comparative Example 5 - - 0.24 g 7 g 63 g 280 g 20% 300-327 nm Reference Example 7 0.23 g - - 5.25 g 47.25 g 297.5 g 15% 500-800nm Example 7 - 0.61 g - 5.25 g 47.25 g 297.5 g 15% 1.5-2㎛ Comparative Example 6 - - 0.24 g 5.25 g 47.25 g 297.5 g 15% 10-12nm

Initiator ^* 1: initiator of the formula (II) prepared in Reference Example 1

Initiator ^* 2: [initiator of formula (I) of the present invention prepared in Example 1

Initiator ^* 3: potassium persulfate as the conventional initiator (K2S2O8)

^* Crosslinking agent: divinylbenzene

^* Monomer: Methyl methacrylate

^The particle size was measured by a scanning electron microscope.

The particle size or particle distribution in Examples 2 to 4 and Reference Examples 2 to 4 and Comparative Examples 1 to 3 fixed the solids content to 17% and the concentration of the initiator was in It is a value according to the type of each initiator when changed to.

Initiator 1 had one functional group, while initiator 2 had two functional groups, so that even when the same concentration of initiator was added, the particle size was observed to be larger, but the particle size did not increase linearly with respect to the functional group. I could confirm that.

In the case of the initiator 3, the reaction time was about two to three times higher than the initiators 1 and 2 due to the polymerization by heat, the size of the particles appeared small, and the distribution of the particles was also secondary, so that the distribution of the particles was wide.

The particle size or particle distribution in Examples 5-7 and Reference Examples 5-7 and Comparative Examples 4, 5 increased the solids content to 25% and increased the concentration of the initiator. It is a value according to the type of each initiator when fixed to, Example 7, Comparative Example 7 and Comparative Example 6 reduces the content of solids to 15% and the concentration of the initiator When fixed to the value according to the type of each initiator.

From the results of Table 1, when the content of the solid content is 25% or more, the size of the particles rapidly increases due to the agglomeration of the particles, but the particle size distribution tends to deteriorate, and when the content of the solid content is lower than 15%, It was confirmed that the size was too small and the polymerization time also tended to be long. In particular, in the case of using the conventional initiator 3, it has been found that when the solid content is 25%, the size of the particles rapidly increases due to the aggregation between the particles, so that the distribution of the particles appears widely.

As described above, the production of polymethyl methacrylate powder having a more uniform particle size distribution is performed simply and effectively by a living radical polymerization method using ultraviolet rays of 254 nm or 365 nm using the novel initiator according to the present invention. The reaction time can be reduced by two to three times compared with the conventional nitroxide method or RAFT method, and the complex process of separating transition metals in the polymer purification process as in the conventional ATRP method can be performed. In addition to the needlessness, only by controlling the initiator content, the size of the particles can be adjusted to obtain particles of a desired size. Particles produced by the manufacturing method of the present invention can be used as a raw material for improving the usability of color cosmetics or powder of toner binder or sunscreen cream, functional cosmetics.

Claims (4)

Living radical initiator for polymer polymerization represented by the following structural formula (I): (Structure Formula (I)) Method for producing a polymethyl methacrylate powder, characterized in that carried out by the emulsion polymerization method or suspension polymerization method using the living radical initiator according to claim 1. The method for producing a polymethyl methacrylate powder according to claim 2, wherein the manufacturing method uses light having a wavelength of 250 to 380 nm. (delete)