KR100772931B1 - Process for preparing fully crosslinked polymer particles using block copolymer synthesized by the living free radical polymerization - Google Patents

Abstract

A method for preparing a vinyl-based polymer particle is provided to prepare a vinyl-based polymer particle having an average diameter of 1-50 micrometers by single process and to allow the specific surface area of crosslinked particles to be controlled easily. A method for preparing a vinyl-based polymer particle comprises the step of polymerizing a crosslinking agent or a mixture of a crosslinking agent and an unsaturated vinyl-based monomer, a polymerization initiator and a reactive stabilizer in a solvent, wherein the crosslinking agent is at least one selected from divinyl benzene and acrylate compound, the reactive stabilizer is an amphiphilic block copolymer comprising a water-soluble polymer block and an oil-soluble polymer block and is prepared by reversible addition-fragmentation chain transfer polymerization, and the polymerization is carried out with stirring with 10-300 rpm at 50-100 deg.C for 1-12 hours.

Description

Process for preparing fully crosslinked polymer particles using block copolymer synthesized by the living free radical polymerization}

1 is an electron micrograph (SEM) of the spherical polymer particles prepared in Example 3.

2 is a transmission electron microscope (TEM) photograph of the spherical polymer particles prepared in Example 3.

FIG. 3 shows spherical polymer particles prepared by changing the amount of divinylbenzene used as a crosslinking agent with respect to styrene monomers in Examples 3 and 6 to 8 (25:75, 50:50, 75:25, 100: 0). The results are analyzed by differential scanning calorimetry (DSC).

The present invention relates to a method for producing a cross-linked spherical vinyl polymer particles, in particular a parent made through reversible addition-fragmentation chain transfer polymerization (RAFT), one of the living free radical method The present invention relates to a method for preparing polymer particles in a single step using crosslinkable block copolymers having an average particle diameter of 1 to 50 microns and easily controlling the specific surface area of the particles by using a block copolymer as a reactive stabilizer.

Block copolymers prepared by the reversible addition-breaking chain transfer polymerization method, which is one of living free radical polymerization methods, have various chains such as dithioester, dithiocarbamate and xanthaite. It has been reported that the use of a transfer agent can control the molecular weight at will and obtain a very narrow molecular weight distribution [Comprehensive Polymer Science; Pergamon: London, vol 3, p 141 (1989), Macromolecules, 27, 638 (1994), Japanese Patent No. 04198303 and Korean Patent No. 0385724]. The reaction mechanism of the block copolymer prepared by the reversible addition-break chain transfer polymerization method is as follows.

Generally, polymerization methods for preparing crosslinked vinyl polymer particles include suspension polymerization, emulsion polymerization, seeded polymerizaton, dispersion polymerization, and precipitation polymerization. Each manufacturing method has advantages and disadvantages.

Suspension polymerization is a method of preparing polymer particles by adding a monomer insoluble to water as a dispersion medium in the presence of a dispersion stabilizer of a polymer and dispersing it in an aqueous solution using a mechanical force, and then polymerizing monomer droplets using a fat-soluble initiator. The manufacturing method has the advantage that the particles can be obtained in a single process, but since the monomers must be dispersed by physical force, there is a difficulty that the prepared polymer has a very wide particle size distribution of 0.1 to 1000 microns. Therefore, the crosslinked polymer prepared through the suspension polymerization method has an average diameter of 100 microns or more (US Pat. Nos. 4,017,670, 4,017,670, 4,085,169, and 4,129,706). In order to lower the particle size distribution, a method of separating and preparing particles formed of various sizes using an additional mechanical device has been studied (Japanese Patent No. 90-261628). However, the complex classification device is costly and labor-intensive and has the disadvantage of very low practical productivity.

Emulsion polymerization can produce cross-linked polymer particles of uniform size of about 1 micron in diameter in a single process, but it is difficult to produce particles with diameters larger than that, and the surfactant used for the formation and stability of the particles is particles. Adsorbed on the surface of the foam is not easy to remove or remove the physical properties of the formed polymer has a disadvantage.

Seed polymerization is a method for producing polymer particles having a uniform particle size distribution in microns by swelling the monomers after redispersing the particles of uniform size prepared by emulsion polymerization or dispersion polymerization in the dispersion medium. 4,459,378, 6,228,925, and 4,996,265, European Patent 326,383, Japanese Patent Nos. 62-273,215 and 05-222,204. While the seed polymerization is easy to control the particle size, the polymerization procedure is very demanding and the two- or three-stage polymerization process requires a long time.

Dispersion polymerization is spherical or more than 1 micron using an organic solvent or a mixed solvent of organic solvent and water, a steric stabilizer and a fat-soluble initiator that are soluble in the vinyl monomer and the monomer, and are insoluble in the polymer particles produced by the dispersion polymerization. It is a polymerization method for producing polymer particles. In order to obtain crosslinked particles using this dispersion polymerization method, the maximum amount of crosslinking agent that can be crosslinked is not more than 5% by weight relative to the monomer, and when it is added more, the polymer particles agglomerate to each other or are irregularly shaped particles There is a difficult problem in producing the fully crosslinked particles are formed.

Finally, precipitation polymerization is relatively homogeneous, and the basic principle is similar to dispersion polymerization.However, unlike dispersion polymerization, the particles themselves form spherical particles by crosslinking in the particles without using a stabilizer. Since the method is maintained in the US Patent No. 5,599, 889] there is no unreactive material, the purity of the particles produced is high. However, precipitation polymerization has a limitation in that the types of monomers available and the solvents used as cosolvents are extremely limited.

Various methods of obtaining crosslinked polymer particles have been studied and developed so far, but it is still difficult to prepare spherical particles having a large content of crosslinking agent and a specific surface area of polymer particles in a single reproducible process.

The present invention provides a method for producing cross-linked spherical polymer particles using a block copolymer made through a reversible addition-break chain transfer polymerization method as a reactive stabilizer. Particularly, the present invention provides a high degree of crosslinking in a single reproducible process. An object of the present invention is to produce spherical particles having a specific surface area of the polymer particles having a large diameter.

To this end, the present inventors used the block copolymer made through the reversible addition-breaking chain transfer polymerization method as a reactive stabilizer in the free radical polymerization method, which is one of the studies for forming spherical polymer particles, and the content of the crosslinking agent and the specific surface area of the particles. It was found that the control can be completed the present invention.

Accordingly, the present invention is a polymer which is crosslinked using a crosslinking agent alone or a monomer mixture having a high crosslinking agent content in a single process using a block copolymer made through a reversible addition-breaking chain transfer polymerization method as a reactive stabilizer and having a higher specific surface area of the particles. The purpose is to provide a method for producing the particles.

In the present invention,

Crosslinking agents or mixtures of crosslinking agents and unsaturated vinyl monomers; Polymerization initiator; In the method for producing a crosslinked polymer particles by polymerizing a reactive stabilizer on a solvent,

The cross-linking agent is used at least one selected from divinylbenzene or acrylate-based, and using an amphiphilic block copolymer made through a reversible addition-break chain transfer polymerization method as the reactive stabilizer, 50 ~ 100 ℃ Provided is a method for producing vinyl polymer particles, characterized in that a crosslinked spherical polymer particle having an average particle diameter of 1 to 50 μm is obtained by a single step of polymerization at a stirring speed of 10 to 300 rpm for 1 to 12 hours at a temperature. .

As the crosslinking agent in the present invention, one or two or more selected from divinylbenzene or acrylate may be used. As an acrylate crosslinking agent, 1,2-ethanediol diacrylate; 1,3-propanedioldiacrylate; 1,3-butanediol diacrylate; 1,4-butanediol diacrylate; 1,5-pentanediol diacrylate; 1,6-hexanediol diacrylate; Ethylene glycol diacrylate; Propylene glycol diacrylate; Butylene glycol diacrylate; Triethylene glycol diacrylate; Polyethylene glycol diacrylate; Polypropylene glycol diacrylate; Polybutylene glycol diacrylate; Alkyl acrylates; 1,2-ethanedioldimethacrylate; 1,3-propanediol methacrylate; 1,3-butanedioldimethacrylate; Ethylene glycol dimethacrylate; Propylene glycol dimethacrylate; Butylene glycol dimethacrylate; Triethylene glycol dimethacrylate; Polyethylene glycol dimethacrylate; Polypropylene glycol dimethacrylate; Polybutylene glycol dimethacrylate; Allyl methacrylate; Urethane acrylate; Diallyl maleate and the like can be used. The crosslinking agent may be used alone or in combination with the unsaturated vinyl monomer. The total mass of the crosslinking agent and the unsaturated vinyl monomer used is preferably 1 to 50% by weight based on the solvent used. If the amount of use is less than 1% by weight, the economical efficiency is reduced, and if the amount exceeds 50% by weight, the stability of particles to be formed decreases, causing agglomeration and a problem that a stable spherical particle cannot be obtained.

In the present invention, as a reactive stabilizer, an amphiphilic block copolymer made through a reversible addition-breaking chain transfer polymerization method, which is one of general living free radical polymerization methods, is used. In this block copolymer, one block is a water-soluble polymer and the other block is composed of a fat-soluble polymer. Preferably, a vinylpyridine compound as the water-soluble polymer; Vinyl acetate compounds; Vinyl alcohol compounds; Ethylene glycol-based compounds and the like can be used, the fat-soluble polymers are aromatic vinyl-based compounds; Cyan vinyl compound; Acrylate compound; Methacrylate type compounds; Diacrylate type compound; Dimethacrylate-based compounds and the like can be used. The block copolymer is preferably used in an amount of 0.1 to 30% by weight, more preferably 1 to 20% by weight, based on the total mass of the crosslinking agent and the unsaturated vinyl monomer used. If the amount of the block copolymer is too small, a large amount of nano-sized particles are formed in excess, so that many particles that do not participate in micron-sized particles are formed, thereby decreasing the uniformity and yield of the overall polymer particles. On the other hand, when used beyond the above range, agglomeration of micron-sized particles occurs, which causes problems.

Unsaturated vinyl monomers can be used as long as they can be radically initiated, which are used in general dispersion polymerization, emulsion polymerization or suspension polymerization. Preferably aromatic vinyl compounds; Cyan vinyl compound; Acrylate compound; Methacrylate type compounds; Diacrylate type compound; And dimethacrylate type compound etc. can be used together 1 type (s) or 2 or more types. Specifically, styrene; Divinylbenzene; Ethyl vinyl benzene; Alphamethylstyrene; Fluorostyrenes; Vinylpyridine; Vinyl chloride; Acrylonitrile; Methacrylonitrile; Butyl acrylate; 2-ethylhexylethyl acrylate; Glycidyl acrylate; N, N'-dimethylaminoethyl acrylate; Butyl methacrylate; 2-ethylhexylethyl methacrylate; Methyl methacrylate; 2-hydroxyethyl methacrylate; Glycidyl methacrylate; Polyethylene glycol diacrylate; 1,3-butylene glycol diacrylate; 1,6-hexanediacrylate; Ethylene glycol dimethacrylate; Diethylene glycol dimethacrylate; Triethylene glycol dimethacrylate; Polyethylene glycol dimethacrylate; 1, 3- butylene glycol dimethacrylate etc. can be used together 1 type (s) or 2 or more types. At this time, the surface shape of the particles to be produced will vary depending on the type of monomer used.

The polymerization initiator used in the present invention has a property of initiating radical decomposition and addition polymerization of monomers in the presence of heat and a reducing substance. As the polymerization initiator, known fat-soluble or water-soluble initiators are used. Preferably, one or a mixture of two or more selected from peroxides, azo compounds, percarbonate compounds and perester compounds may be used. For example, acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate; Benzoyl peroxide; 2,2'-azobisisobutyronitrile; Azobis-2,4-dimethylvaleronitrile; Azobis (4-methoxy-2,4-dimethylvaleronitrile); Di-isopropyl peroxydicarbonate; Di-2-ethylhexyl peroxydicarbonate; Dioctoxyethyl peroxydicarbonate; α-cumyl peroxyneodecanate; t-butyl peroxy neodecanate, etc. can be used. The polymerization initiator is preferably used at 0.01 to 5% by weight of the total mass of the unsaturated vinyl monomer and the crosslinking agent used, more preferably at 0.05 to 3% by weight. If the amount of use is less than 0.01% by weight, there is a problem that the rate of the polymerization reaction is significantly reduced, and when the amount exceeds 5% by weight, very small particles are formed, thereby making the distribution of particles even wider.

The solvent is preferably used by mixing the crosslinking agent and an organic solvent capable of dissolving the unsaturated vinyl monomer and water as a cosolvent. The organic solvent that can be used is preferably one or two or more selected from alcohols, ether alcohols, ketones and phenyls. For example, methanol; ethanol; Isopropyl alcohol; Butyl alcohol; Octyl alcohol; Benzyl alcohol; Cyclohexanol; Ethylene glycol; Glinerol; Diethylene glycol; Methyl cellosolve; Cellosolves; Butyl cellosolve; Isopropyl cellosolve; Ethylene glycol monomethyl ether; Ethylene glycol monoethyl ether; Diethylene glycol monomethyl ether; Diethylene glycol monoethyl ether; Acetone; Methyl ethyl ketone; Methyl isobutyl ketone; Chlorobenzene; benzene; Toluene and the like can be used. Water can be used in 20 to 80% by weight of the organic solvent, preferably 30 to 70% by weight.

The polymerization reaction was carried out at 10 to 300 rpm stirring rate for 1 to 12 hours at a temperature of 50 to 100 ℃ by mixing a crosslinking agent alone or a mixture of a crosslinking agent and an unsaturated vinyl monomer, a free radical initiator and a block copolymer in a predetermined ratio on the solvent. When the nano-sized particles are formed, they are physically or chemically bonded to each other to form a cross-linked stable spherical polymer particles. The reaction time is shorter than the conditions under which general radical polymerization can be made to form a polymer, and it is another feature of the present invention to obtain cross-linked micron-sized particles in less time. In addition, since nano-size particles combine to form a single particle, the specific surface area of the formed particles is larger than that of general crosslinked particles, and the degree of adjustment can be easily adjusted according to reaction conditions. Can be.

The crosslinked spherical polymer particles having various sizes and large specific surface areas prepared according to the present invention may be filled with chromatography columns, functional / analytical diagnostic reagents, drug delivery materials, catalyst carriers, and anisotropy according to their characteristics. It can be used in various and high value-added industries such as conductive balls and light diffusion films.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the scope of the present invention is not limited by the following examples, and those skilled in the art to which the present invention pertains should be within the equivalent scope of the technical concept of the present invention and the claims to be described below. Of course, various modifications and variations are possible.

Block copolymer  synthesis

First step

In a nitrogen atmosphere, 40 ml of styrene washed with a polymerization inhibitor with a diluted caustic soda solution, 0.01 g of 2,2'-azobisisobutyronitrile as an initiator and 0.2 g of 4-toluic acid dithiobenzoate as a chain transfer agent After stirring for 20 minutes in a completely closed reactor, the temperature was heated to 70 ℃ and reacted for a certain time, after the leaching process using alcohol and dried to prepare a polystyrene with a pink chain transfer agent. The number average molecular weight and molecular weight distribution (PDI) of the obtained polystyrene were confirmed by gel permeation chromatography (GPC) and are shown in Table 1 below.

2nd step

5 g of 4-vinylpyridine and dimethylformamide (DMF) obtained by washing the polymerization inhibitor by the same method as 1 g of polystyrene obtained above, 2,2'-azobisisobutyronitrile as an initiator, and 0.02 g of styrene. 10ml was stirred for 20 minutes in a nitrogen atmosphere and completely mixed.Then, it was transferred to a closed reactor, heated to 70 ° C, and reacted for a predetermined time. After leaching and drying, a pale scarlet color with controlled molecular weight and narrow molecular weight distribution was obtained. A block copolymer in which polystyrene and a poly 4-vinylpyridine to which a chain transfer agent was added was connected in blocks was prepared. The polymerization of the block copolymer was confirmed by nuclear magnetic resonance spectroscopy (NMR, nuclear magenetic resonance). The number average molecular weight and molecular weight distribution (PDI) of the obtained block copolymers were confirmed by gel permeation chromatography (GPC, Gel Permeation Chromatography) and are shown in Table 1 below.

Polymerization of Crosslinked Particles

Example  1 to 5

In a three-neck round flask reactor equipped with a cooler, 50 ml of ethyl alcohol, 50 ml of water, 0.1 g of 2,2'-azobisisobutyronitrile, 10 g of divinylbenzene as a crosslinking agent, and the block copolymer synthesized above were The mixture was added at a constant amount with respect to the concentration of vinylbenzene, and stirred at room temperature to confirm that the mixture became homogeneous. The mixture was then placed under a nitrogen atmosphere, and polymerized for 6 hours while maintaining a stirring speed of 100 rpm and a temperature of 70 ° C. Divinylbenzene polymer was obtained. As a result of centrifugation and analysis by SEM and TEM, it was confirmed that a stable spherical particle was formed and that the inside of the particle had porosity. 1 is an electron micrograph (SEM) of the spherical polymer particles prepared in Example 3, Figure 2 is a transmission electron microscope (TEM) of the spherical polymer particles prepared in Example 3. The yield etc. of the obtained polymer are shown in Table 2.

Example  6 to 8

Commercially available styrene was washed with the diluted caustic soda solution to remove the polymerization inhibitor and preserved by water.

Prepared in the same manner as in Example 1 except that the styrene monomer was added in a predetermined amount with respect to the concentration of divinylbenzene as a crosslinking agent, and the block copolymer was fixed at 10% by weight of the total mass of divinylbenzene and styrene to prepare the reaction mixture. It was polymerized. The obtained polymer was centrifuged to investigate particle formation and thermal stability through scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results are shown in Table 3. In addition, the thermal properties of the particles according to the addition amount of divinylbenzene (crosslinking agent) to the styrene monomer together with the polymer obtained in Example 3 were analyzed by differential scanning calorimetry (DSC), and the results are shown in FIG. 3 (Example 6 (25), Example 7 (50), Example 8 (75), Example 3 (100)). As a result of the analysis, all of the obtained polymers were spherical, stable particles, and the glass transition temperature was not observed in all samples. Thus, the crosslinking was completely performed. As the content of the crosslinking agent was increased, the thermal properties increased.

Example  9-11

Except for changing the content of ethyl alcohol and water was prepared in the same manner as in Example 1, except that the polymerization of the block copolymer fixed to 10% by weight of the crosslinking agent to bind the small particles of one crosslinked particle Was formed. As a result of centrifugation and analysis by electron microscope, it was confirmed that all of the particles were stable spherical particles. The results are shown in Table 4 below.

Example  12-14

Prepared in the same manner as in Example 1, various unsaturated vinyl monomers were used in the same amount as the divinylbenzene crosslinking agent, and the amount of block copolymer was fixed at 1 g to obtain crosslinked particles in the form of small particles. The yields of particles using various unsaturated vinyl monomers and divinylbenzene, and centrifugation were analyzed by electron microscopy and measured using a specific surface area measuring apparatus (BET).

Example  15-16

Prepared in the same manner as in Example 1, using different initiators, the amount of block copolymer was fixed to 1g to obtain spherical stable crosslinked particles. The formed particles were centrifuged and analyzed by electron microscopy, and all of them were found to be stable spherical particles. The yield and the like are shown in Table 6 below.

Example  17-18

Prepared in the same manner as in Example 1, the amount of stabilizer used was fixed to 1g and using the block copolymer and macromonomer used in the present invention as a reactive stabilizer was attempted to obtain spherical particles. As a result of centrifugation of the formed particles, an electron microscope analysis showed that spherical stable particles having a large specific surface area were formed only in the case of block copolymers. It was confirmed that particles having a small surface area were obtained.

In the present invention, to overcome the limitations of the production of polymer particles with too wide a size distribution or poor crosslinking degree, to prepare a polymer particle that can control the surface area between 1 and 50 microns in a single process. The crosslinked polymer particles prepared according to the present invention may form particles even with a single crosslinkable monomer, may be copolymerized with various vinyl monomers, and variously control the state of the particle surface according to reaction conditions. The cross-linked spherical vinyl polymer particles prepared according to the present invention are used in various industries such as packing materials for chromatography columns, diagnostic reagents for functional / analysis, drug delivery materials, catalyst carriers, anisotropic conductive balls, and light diffusion films. Can be used.

Claims (6)

Crosslinking agents or mixtures of crosslinking agents and unsaturated vinyl monomers; Polymerization initiator; In the method for producing a crosslinked polymer particles by polymerizing a reactive stabilizer on a solvent, One or two or more selected from divinylbenzene and an acrylate type are used as the crosslinking agent; As the reactive stabilizer, an amphiphilic block copolymer made of a reversible addition-break chain transfer polymerization method and one block is a water-soluble polymer and the other block is made of a fat-soluble polymer; Production of vinyl polymer particles characterized in that crosslinked spherical polymer particles having an average particle diameter of 1 to 50 μm are obtained by a single step of polymerization at a temperature of 50 to 100 ° C. at a stirring speed of 10 to 300 rpm for 1 to 12 hours. Way. The method of claim 1, wherein the water-soluble polymer is a vinylpyridine compound; Vinyl acetate compounds; Vinyl alcohol compounds; One of the ethylene glycol compounds, the fat-soluble polymer is an aromatic vinyl compound; Cyan vinyl compound; Acrylate compound; Methacrylate type compounds; Diacrylate type compound; It is one of the dimethacrylate-based compounds. The acrylate-based crosslinking agent according to claim 1 or 2, comprising 1,2-ethanediol diacrylate; 1,3-propanedioldiacrylate; 1,3-butanediol diacrylate; 1,4-butanediol diacrylate; 1,5-pentanediol diacrylate; 1,6-hexanediol diacrylate; Ethylene glycol diacrylate; Propylene glycol diacrylate; Butylene glycol diacrylate; Triethylene glycol diacrylate; Polyethylene glycol diacrylate; Polypropylene glycol diacrylate; Polybutylene glycol diacrylate; Alkyl acrylates; 1,2-ethanedioldimethacrylate; 1,3-propanediol methacrylate; 1,3-butanedioldimethacrylate; Ethylene glycol dimethacrylate; Propylene glycol dimethacrylate; Butylene glycol dimethacrylate; Triethylene glycol dimethacrylate; Polyethylene glycol dimethacrylate; Polypropylene glycol dimethacrylate; Polybutylene glycol dimethacrylate; Allyl methacrylate; Urethane acrylate and diallyl maleate. The method of claim 3, wherein the unsaturated vinyl monomer, Styrene; Divinylbenzene; Ethyl vinyl benzene; Alphamethylstyrene; Fluorostyrenes; Vinylpyridine; Vinyl chloride; Acrylonitrile; Methacrylonitrile; Butyl acrylate; 2-ethylhexylethyl acrylate; Glycidyl acrylate; N, N'-dimethylaminoethyl acrylate; Butyl methacrylate; 2-ethylhexylethyl methacrylate; Methyl methacrylate; 2-hydroxyethyl methacrylate; Glycidyl methacrylate; Polyethylene glycol diacrylate; 1,3-butylene glycol diacrylate; 1,6-hexanediacrylate; Ethylene glycol dimethacrylate; Diethylene glycol dimethacrylate; Triethylene glycol dimethacrylate; Polyethylene glycol dimethacrylate; And 1,3-butylene glycol dimethacrylate. The solvent according to claim 3, wherein the solvent is a mixed solvent in which an organic solvent and water are cosolvents, and the organic solvent is an alcohol; Ether alcohols; Ketones Phenyl-based solvent, characterized in that the production method. The method of claim 3, wherein the polymerization initiator is selected from a peroxide, an azo compound, a percarbonate compound, and a perester compound.

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