KR20090024396A - Manufacturing method for fine polymer particles using dimethylether - Google Patents

Abstract

A method for synthesizing a polymer microparticle using DME(dimethyl ether) is provided to polymerize monomers to obtain a polymer microparticle in no need of a process of separating a solvent. A method for synthesizing a polymer microparticle using DME(dimethyl ether) comprises the following steps of: mixing a monomer, initiator, dispersing agent, and DME(demethyl ether) as a solvent in a reactor; polymerizing a polymer with above described materials at a temperature of 50-80 °C with a pressure of 20 bar or greater; and decompressing and removing the DME to obtain a pure polymer microparticle.

Description

Manufacturing Method For Fine Polymer Particles Using Dimethylether

The present invention relates to a method for synthesizing polymer microparticles, and more particularly, polymer microparticles having high value for use in various industrial fields such as cosmetics, electronic materials, and DDS through a dispersion polymerization mechanism using dimethyl ether in a compressed liquid region as a polymerization solvent. In particular, the present invention relates to a technique for producing spherical polymer fine particles.

In recent years, the development of polymer fine particles has been actively progressed, and has been widely used in various industrial applications. Among them, polymer particles having a spherical particle shape and a narrow particle size distribution have been used for applications such as filters, membranes, dispersants, powder coatings, resin modifiers, and coating agents because of their good processability, fluidity, and surface properties.

These polymer fine particles have a very large surface area per unit volume and exhibit very different properties compared to other physical and chemical materials. Conventional methods for making micronized polymers include microemulsion polymerization, emulsion polymerization, dispersion polymerization, suspension polymerization, etc. The conventional method has a problem of using a solvent and removing the solvent after polymerization. It is not environmentally friendly and takes a lot of cost in the separation process, and most of the solvents are combustible organic solvents, and there are various problems such as process safety due to ignition.

In order to solve the above problems, researches for producing fine particles using water as a reaction solvent are being actively conducted, but even in this case, high purity such as application fields or electronic and information materials, which should be less irritating to the human body, such as medicine or cosmetics In applications that require the use of complex separation processes for the removal of emulsifiers or residual monomers, there is a problem.

In order to solve this problem, a solution, precipitation, and dispersion polymerization method using non-toxic, environmentally friendly, inexpensive and nonflammable supercritical carbon dioxide as a reaction solvent in addition to the above polymerization method have been proposed, and various groups have been researching.

The supercritical carbon dioxide has gas-like diffusivity and penetration and liquid-like density and solubility with low viscosity and near zero surface tension. In addition, due to the relatively low critical temperature and critical pressure (31.1 ℃, 73.8 bar), there is an advantage that can easily reach the supercritical state, among the supercritical fluids used in the polymerization reaction for synthesizing various types of polymer materials Most widely studied.

However, since the polymerization using the supercritical carbon dioxide has to maintain a high pressure, the production of a high pressure vessel is required and the possibility of safety problems increases. In addition, since a high pressure pump is necessary to pressurize to the desired pressure, not only a lot of energy is consumed in the polymerization process but also a lot of costs are required for the production of supercritical polymerization equipment. Cost is required.

In addition, supercritical carbon dioxide has a disadvantage in that the monomers that can be polymerized are extremely limited because of low solubility in monomers of polarity, and the initial investment is expensive because a high pressure reactor and a high pressure pump must be used.

Regarding the synthesis of polymers using supercritical carbon dioxide, U.S. Patent Publication No. 5,884,94 discloses a method of synthesizing a fluorine-based polymer using liquid carbon dioxide and supercritical carbon dioxide. Also, Korean Patent Registration No. 735840 discloses a supercritical material of high temperature and high pressure. Although a technique for preparing a porous polymer using carbon dioxide as a polymer synthetic solvent has been proposed, the methods using the supercritical carbon dioxide have a problem in that the manufacturing of the equipment and the process operation are expensive because the process is performed at a high pressure.

The present invention is characterized in that the solvent evaporates after the synthesis of the polymer fine particles, which is an advantage in the method of synthesizing the polymer using supercritical carbon dioxide, does not remain in the polymer fine particles. There is a need to provide a novel method for synthesizing polymer particles that is easy and inexpensive to design a reactor because it is not required.

That is, the present invention enables the polymerization at a relatively low pressure than the supercritical by using a solvent in the compressed liquid region rather than supercritical, does not require complicated high pressure equipment, thereby greatly reducing the initial investment costs To recover the polymer particles immediately by lowering the pressure without a separate separation process, it is to provide a method for synthesizing the polymer particles to significantly reduce the time and energy required.

In addition, in another object of the present invention, when the supercritical carbon dioxide is used as a polymerization solvent, an organic solvent may be added as a cosolvent because of low solubility in polar monomers. In the case of the polymer used as a problem, even if the residual solvent is removed, an additional separation process is required. Therefore, dispersion polymerization is performed using dimethyl ether in the compressed liquid region as a polymerization solvent to give polar monomers. Another object of the present invention is to provide a method for synthesizing polymer fine particles, which enables polymerization.

In order to achieve the above object, the present invention provides a method for synthesizing polymer fine particles from monomers, in which a dimethyl ether is mixed as a polymerization solvent together with a monomer, an initiator and a dispersant in a reactor, and the pressure condition is 20 bar or more and the temperature condition is 50 ° C. or more. After completing the polymerization of the polymer fine particles at 80 ℃, by decompression to provide a method for synthesizing the polymer fine particles using dimethyl ether, characterized in that the polymer fine particles are obtained by evaporating the solvent dimethyl ether.

Moreover, it is preferable that the said monomer is a polar monomer melt | dissolved in dimethyl ether.

In addition, the polymer fine particles prepared by the above synthesis method PVK (poly (N-vinylcarbazole)), PVCL (poly (N-vinyl caprolactam)), PVP (poly (N-vinyl pyrrolidone)), PHEMA (Poly (2- hydroxyethyl methacrylate)), PHPMA (poly (2-hydroxypropyl methacrylate)), PGMA (poly (2-glycidyl methacrylate)), PAN (poly (acrylonitrile)) is preferably any one selected from.

In addition, the initiator is preferably any one selected from 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'- azobisisobutyronitrile (AIBN), dimethyl 2,2'-azobis (isobutyrate).

In addition, the shape of the polymer fine particles produced by the method is characterized in that the sphere.

In the method for synthesizing the polymer fine particles according to the present invention, by using dimethyl ether in a compressed liquid state as a polymerization solvent, when the polymer fine polymer is polymerized and decompressed to atmospheric pressure, dimethyl ether is vaporized and removed, compared to a polymerization using a general organic solvent. No solvent separation is necessary.

In addition, the equipment can be manufactured without additional high pressure additional equipment such as a high pressure pump such as a polymerization method using a carbon dioxide supercritical, thereby reducing the initial investment cost.

In addition, the polymerization of polar monomers was very difficult in carbon dioxide supercritical, but in the present invention, since polar dimethyl ether is used as a solvent, polymerization of various polar monomers is possible.

Hereinafter, a method for synthesizing the polymer fine particles according to a preferred embodiment of the present invention in more detail. In particular, the polymer fine particles produced by the present invention is characterized by having a spherical shape.

As described above, the method for synthesizing the polymer fine particles of the present invention is characterized by synthesizing the polymer fine particles through dispersion polymerization using dimethyl ether in a compressed liquid state as a reaction solvent.

Dimethyl ether consists of the molecular structure of CH ₃ OCH ₃ , which is the simplest ether form, and exists as a gas under normal temperature and pressure. Dimethyl ether is mainly used as a propellant for aerosols, or research is being actively conducted for use as a fuel. Such dimethyl ether has not been found to be applied as a solvent for polymer synthesis until now. This is because, unlike high-pressure, high-temperature polymer synthesis reactions such as supercritical fluid, polymer synthesis using an organic solvent mainly synthesizes the polymer using a solvent which is a liquid phase at normal temperature and pressure. The present invention dissolves the monomer of polarity, which is an advantage of dimethyl ether, and is present as a gas at room temperature and normal pressure. The present invention has been completed with the advantage that the ether is removed by evaporation with gas.

The polymerization method of the present invention uses a dispersion polymerization method. In the following examples, the dispersion polymerization was performed in a reactor composed of 30 ml of internal capacity and SUS 316. A viewing window using a tempered glass having a diameter of 13 mm and a thickness of 13 mm was installed at the bottom of the reactor to observe the inside of the reactor, and a magnetic stirring bar coated with Teflon was used for stirring.

First, reactants such as monomers, initiators, and dispersants were placed in the reactor, and dimethyl ether was injected into the reactor.

Here, the initiator is preferably used at least one selected from 2,2'-azobis (2,4-Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile (AIBN), dimethyl 2,2'-Azobis (isobutyrate) , The dispersant is preferably used among fluorine-based dispersant poly (HDFDMA) and poly (HDFDA), modified silicone dispersant monasil PCA, SS-5050K, KF-6017, but the scope of the present invention is specific It is not limited to the kind of initiator and a dispersing agent. Conventional polymer synthesis initiators and dispersants can be used.

Dimethyl ether is easily liquefied by applying pressure at 25 ° C. to 6 bar. Therefore, in the method of injecting dimethyl ether, the reactor is first cooled with ice water or the like, and then dimethyl ether is contained in a cylinder and injected into the reactor in a liquefied state. At this time, the amount injected into the reactor can be measured by measuring the weight before and after the injection of the cylinder of dimethyl ether, and the same amount can be injected for each experiment.

The polymerization reaction was carried out in a constant temperature water bath to minimize the temperature change during the polymerization process. When the temperature rises to the polymerization temperature, the pressure is automatically set to the set pressure. Stirring inside the reactor was used a stirrer that can be used in a constant temperature water bath.

After completion of the polymerization, dimethyl ether was gaseous at room temperature and atmospheric pressure, and was then discharged directly into the atmosphere through two glass traps made of glass. The outside of the trap was cooled, and the inside of the trap was filled with methanol, which dissolves the monomer well, to prevent harmful substances from being released into the atmosphere. After all of the dimethyl ether was discharged, the lid of the reactor was opened to recover the synthesized polymer fine particles.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

Example  1 to 7

Poly (N-vinylcarbazole) (PVK) as Example 1, poly (N-vinyl caprolactam) (PVCL) as Example 2, poly (N-vinyl pyrrolidone) (PVP) as Example 3, PHEMA (Example 4) Poly (2-hydroxyethyl methacrylate)), PHPMA (poly (2-hydroxypropyl methacrylate)) as Example 5, PGMA (poly (2-glycidyl methacrylate)) as Example 6, PAN (poly (acrylonitrile)) as Example 7 Dispersion polymerization was carried out. The amount of initiator (AIBN) was 1% by weight and the amount of DME was 19 ± 0.5% by weight of solvent. The polymerization temperature and pressure were kept constant at 60 ° C. and 20 bar and reacted for 24 hours.

Each polymer was analyzed by Scanning Electron Microscope (SEM), and the size of the particles was measured by an image analyzer using an SEM image. The results are shown in Table 1 below and FIGS. 1 to 7.

TABLE 1

Example  8 to 10

PHPMA was examined for changes in particle size and molecular weight depending on the amount of initiator. The polymerization temperature and pressure were kept constant at 60 ° C. and 20 bar, and the amount of DME was used as a solvent of 19 ± 0.5 wt%. The shape and size of the particles after polymerization were measured by SEM analysis (see FIGS. 8 to 10) and an image analyzer, and molecular weight was measured by GPC (see FIG. 11). The results are shown in Table 2 below.

TABLE 2

Example  11 and 12

PVK was examined for the change of particle with the change of pressure. In Example 11, the amount of DME was used 19 ± 0.5 wt%, and in Example 12, 21.5 ± 0.5 wt%.

Each polymer was subjected to SEM analysis, and the size of the particles was measured by an image analyzer using an SEM image. The results are shown in Table 3 below and FIGS. 12 and 13.

Unlike the experiments on supercritical carbon dioxide as shown in the results of Table 3 below, the polymerization in dimethyl ether all showed the same results at 20 bar or at a high pressure of 210 bar as shown in Table 3 and FIGS. 12 and 13. Could.

TABLE 3

 When using the polymerization solvent of the present invention from the results of Table 1, Table 2 and Table 3, it is possible to synthesize various spherical polymer fine particles even at a pressure of 20 bar, it is possible to control the molecular weight by changing the amount of initiator I could confirm it. In addition to the change in the amount of the initiator, it was confirmed that the particle size, molecular weight and the like can be changed by changing various polymerization conditions, that is, the amount of dispersant, the temperature, the amount of the monomer, and the like.

As described above, in the method for synthesizing the polymer fine particles according to the present invention, polymerization is performed using dimethyl ether in a compressed liquid state as a polymerization solvent, and after the polymerization is completed, the dimethyl ether is immediately discharged into the atmosphere. Compared with the conventional polymerization using a conventional organic solvent, which requires an additional separation process to recover the particles after completion, this method does not require such a separation process, thereby saving energy. .

In addition, it is possible to manufacture the equipment without additional high-pressure additional equipment such as a high pressure pump to reduce the initial investment cost, and because the dimethyl ether is polar, there is an advantage that can be polymerized for various polar monomers.

1 to 7 are SEM results of PVK, PVCL, PVP, PHEMA, PHPMA, PGMA, and PAN polymerized on the dimethyl ether of Examples 1 to 7, respectively.

 8 to 10 are SEM results of the polymerized PHPMA according to the change of the amount of the initiator of Examples 8 to 10, respectively.

 11 is a molecular weight analysis using GPC according to the change of the amount of the initiator of Examples 8 to 10.

 12 and 13 are SEM results of PVK polymerized according to the change in pressure of Examples 11 and 12, respectively.

Claims (5)

In the method for synthesizing polymer fine particles from monomers, dimethyl ether is mixed as a polymerization solvent with a monomer, an initiator and a dispersant in the reactor, and polymerization of the polymer fine particles is completed at a pressure condition of 20 bar or more and a temperature condition of 50 ° C. to 80 ° C. Thereafter, the reduced pressure is reduced to vaporize the solvent dimethyl ether to obtain pure polymer fine particles. [Claim 2] The method of claim 1, wherein the monomer is a polar monomer dissolved in dimethyl ether. The method of claim 1, wherein the polymer fine particles prepared by the synthesis method is PVK (poly (N-vinylcarbazole)), PVCL (poly (N-vinyl caprolactam)), PVP (poly (N-vinyl pyrrolidone)), PHEMA (Poly (2-hydroxyethyl methacrylate)), PHPMA (poly (2-hydroxypropyl methacrylate)), PGMA (poly (2-glycidyl methacrylate)), PAN (poly (acrylonitrile)) is a polymer using dimethyl ether, characterized in that any one Synthesis method of fine particles. The method of claim 1, wherein the initiator is any one selected from 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile (AIBN), dimethyl 2,2'-azobis (isobutyrate) Method for synthesizing polymer fine particles using dimethyl ether. The method of synthesizing polymer fine particles using dimethyl ether according to claim 1, wherein the polymer fine particles produced by the method are spherical.

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