CS236589B1 - Preparation method of globural polymer particles - Google Patents

Abstract

Spherical porous particles of copolymers 2-hydroxyethyl methacrylate with ethylene methyl methacrylate less than 50 µm, preferably less than 30jum are prepared by radical aqueous dispersion suspension polymerization environment containing polyvinylpyrrolidone, polyvinyl alcohol and inorganic salt. The particles find use as carriers active substances and as adsorbents and gels in liquid chromatography.

Description

The invention relates to the preparation of spherical polymer particles of a size smaller than SO4 by suspension radical polymerization.

Suspension polymerization typically produces polymer particles of 0.1 to several millimeters in size on an industrial scale. It is difficult to prepare particles smaller than 50 [mu] m and in particular particles smaller than 25 [mu] m, since the mixing efficiency in dispersing the monomer phase in the dispersion medium can only be increased to a technically acceptable level. It is these finest particles that have recently been in demand for high performance liquid chromatography.

The polymer particle size can be reduced according to AO No. 196 794 by utilizing the incompatibility of the prepared polymer with the polymer dispersion medium, whereby the polymer in the spherical form of the particles is separated from the homogeneous monomer solution by polymerization.

This process is very specific since the condition of immiscibility of both polymers must be met. According to MS. No. 233,520, it is possible to reduce the particle size of the polymer by adding a bisulfite adduct with a ketone.

However, at the concentrations of this reagent required to form particles of about 10 µm, a larger proportion of particles smaller than 1 µm is formed, which makes it difficult to purify the polymerization mixture. A more general application has the particle size reduction methods of AO No. 200,302, wherein a polyvinyl alcohol solution is used as the dispersion medium and according to U.S. Pat. U.S. Pat. 137,129, wherein 0.5 to 10% gelatin is used.

However, even these methods are not entirely universal, since for the 2-hydroxyethyl methacrylate-ethylene dimethacrylate copolymer, we have found that the first method does not provide round particles and the second method has proved ineffective.

The above disadvantages are overcome by a process for the preparation of spherical particles of copolymers of 2-hydroxyethyl methacrylate with ethylene dimethacrylate by suspension radical polymerization, characterized in that an aqueous solution containing 0.5 to 5% by weight of polyvinylpyrrolidone having a molecular weight of more than 100,000 is used. 0.001 to 0.5% by weight of polyvinyl alcohol having a molecular weight of more than 70,000 and 0.1 to 5% by weight of inorganic salts such as sodium, potassium or ammonium sulphate, chloride, nitrate or phosphate.

An advantage of the process for preparing the copolymer particles of the invention is that it produces spherical particles less than 50 µm, preferably less than 30 µm. It does not form submicron particles that complicate the cleaning and isolation of copolymers.

The addition of inorganic salts, in conjunction with the polymers of the dispersion medium, promotes the reduction of the particle size of the copolymers. The dispersion medium according to the invention does not interfere with the formation of the porous structure of the copolymers, which is important for its use as carrier of active substances and as adsorbent.

The process of the invention employs conventional, commercially available compounds and is readily feasible on an industrial scale. The products find use as adsorbents in liquid chromatography and as gels in gel permeation chromatography.

Example 1

An aqueous solution of 600 ml of water, 24 g of polyvinylpyrrolidone K - 90 (molecular weight 360,000), 0.25 g of polyvinyl alcohol (Gohsenol GH - 23, molecular weight of 150,000) and 9 g of sulfate was introduced into a 2 liter duplicator polymerizer with anchor stirrer. sodium. To this dispersion medium was added an organic monomer phase consisting of 40.9 g of 2-hydroxyethyl methacrylate, 40.9 g of ethylenedimethacrylate, 108.7 g of cyclohexanol, 9.8 g of dodecanol and 1 g of azo-bis-isobutyronitrile. Oxygen was removed from the polymerization batch with stirring (1000 rpm ^{) by a} stream of nitrogen and heating to 60 ° C initiated polymerization, which was carried out at 60 ° C for 1 hour and at 80 ° C for 9 hours. This produced a spherical copolymer whose 80% by weight had a particle size of less than 25 µm and a mean particle size of 15 µm.

Example 2

A dispersion of 600 ml of water, 12 g of polyvinyl pyrrolidone K-90, 0.12 g of polyvinyl alcohol GH-23, 18 g of sodium chloride, 33.7 g of 2-hydroxyethyl methacrylate, 48 g of ethylenedimethacrylate, 108.7 g of polymer was polymerized according to Example 1. cyclohexanol, 9.8 g dodecanol and 1 g azo-bis-isobutyronitrile. A copolymer was obtained in which 80% by weight had particles of less than 30 µm and a mean particle size of 21 µm.

Example 3

A dispersion of 900 ml of water, 36 g of polyvinylpyrrolidone K-90, 0.37 g of polyvinyl alcohol GH-23, 27 g of Na ₂ HPO ₄ , 4.5 g of KH ₂ PO ₄ , were polymerized according to Example 1,

50.5 g of 2-hydroxyethyl methacrylate, 72.0 g of ethylenedimethacrylate, 188.7 g of cyclohexanol,

12.5 g of dodecanol and 1.5 azo-bis-isobutyronitrile. Eighty percent by weight of the copolymer had particles less than 22 µm and a mean particle size of 13 µm.

Claims (1)

Process for preparing spherical particles of a copolymer of 2-hydroxyethyl methacrylate with ethylene dimethacrylate by suspension radical polymerization, characterized in that an aqueous solution containing 0.5 to 5% by weight of polyvinylpyrrolidone having a molecular weight of more than 100,000, 0.001 to 0.5% by weight of polyvinyl alcohol is used as dispersion medium. having a molecular weight of more than 70,000 and from 0.1 to 5% by weight of inorganic salts of the sodium, potassium or ammonium sulphate, chloride, nitrate or phosphate type.