JPH0418436A - Production of porous resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a porous resin.More specifically, the present invention relates to a method for producing a porous resin. The present invention relates to a method for producing a porous resin with improved operability as an adsorbent.

[Prior art] Porous adsorbents (hereinafter abbreviated as porous adsorbents), which are crosslinked copolymers of aromatic addition-polymerizable monomers, utilize their hydrophobic properties to absorb water in water. It is used to recover useful substances contained in an organic solvent-water mixture by adsorption, or to selectively remove impurities. It is widely practiced in the field of selectively adsorbing and removing impurity components from mixtures.

These actual processes usually involve two types of steps: adsorption of the adsorbed material from a solution onto a porous adsorbent, and elution of the adsorbed material from the porous adsorbent. In order to operate these processes efficiently, it is necessary to improve the diffusion of the adsorbed substance into the porous adsorbent, so that the adsorbent can adsorb the substance quickly and elute the adsorbed substance in a short time. or required.

On the other hand, porous adsorbents can be obtained by conventional manufacturing techniques, such as copolymerization of aromatic addition-polymerizable monomers and crosslinkable monomers. A method is known in which porosity is imparted to a copolymer by carrying out the process in the presence of a solvent that does not dissolve the aromatic crosslinked copolymer but dissolves the monomer.

Furthermore, it has been shown in JP-A-Sho that the porous adsorbent thus obtained can be treated with a Lewis acid catalyst in the presence of an inert solvent to change its pore structure and increase its specific surface area. It is disclosed in the publication No. 60-163903.

[Problems to be Solved by the Invention] However, the porous resin obtained by the method described in JP-A-60-163903 has a pore structure that does not develop in proportion to the increased specific surface area. Often, the diffusion rate of the adsorbed substance is not sufficient and it is difficult to obtain sufficient elubility, which means that a large excess of the elution solvent (hereinafter referred to as It has been found that there are operational problems such as the need for an eluent (abbreviated as eluent).

The present invention relates to a method for further improving conventional porous resins, and the method of the present invention improves the diffusivity of adsorbed substances, and provides porous resins with improved operability, particularly elution properties of adsorbed substances. The purpose is to provide an adsorbent.

[Means and effects for solving the problems] The present invention has a specific surface area of 100 m2/g or more and a pore volume of 0.2 ml/g.
A method for producing a porous resin comprising reacting a crosslinked copolymer of an aromatic addition-polymerizable monomer with a Lewis acid catalyst in the presence of an inert organic solvent with a crosslinked copolymer of an aromatic addition-polymerizable monomer having an average pore radius of 10 nm or more This is the summary.

The present invention will be explained in detail below.

The crosslinked copolymer of the aromatic addition polymerizable monomer that can be used in the method of the present invention is produced by a technique known per se, and is usually a spherical crosslinked copolymer. Examples of the aromatic addition polymerizable monomer constituting the spherical crosslinked copolymer include monovinyl aromatic compounds, specifically styrene,
Examples include vinyltoluene, vinylnaphthalene, and ethylvinylbenzene. Further, examples of the non-conjugated polyvinyl aromatic compound which is a crosslinkable monomer include compounds such as divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, and divinylxylene.

The mixing ratio of these monovinyl compounds and polyvinyl compounds can be changed at any ratio, but the ratio of the polyvinyl compound as a crosslinking agent to the total vinyl compounds is usually 8 to 8.
It is selected in the range of 0% by weight, preferably 15 to 60% by weight.

If the amount of the polyvinyl compound is too low, cracking of the resin spheres or a decrease in strength may occur during the Lewis acid catalyst treatment according to the method of the present invention, which is undesirable. On the other hand, if the amount is too large, harsher reaction conditions will be required for the Lewis acid catalyst treatment, which is industrially unfavorable.

In addition to the aromatic monovinyl and polyvinyl compounds mentioned above, aliphatic monovinyl compounds such as methyl methacrylate, acrylonitrile, 2-hydroxyethyl methacrylate, methacrylic acid, and ethyl acrylate, and fatty acids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. A spherical crosslinked copolymer obtained by adding a group polyvinyl compound in an amount of 0 to 20% by weight based on the total vinyl monomers can also be used as the porous resin according to the method of the present invention.

These monovinyl compounds and polyvinyl compounds are suspension polymerized according to a known method, and at that time, dibenzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, etc. are used as a polymerization initiator. , usually used in an amount of 0.5 to 5% by weight based on the total monomers. The polymerization temperature varies depending on the type and concentration of the polymerization initiator, but is usually selected within the range of 40 to 90°C.

The method for producing these porous crosslinked copolymers is, for example,
Chelate Resin/Ion Exchange Resin 2 Editor: Shusei Hojo Published by Kodansha, (May 1, 1976 1st edition, pp. 135-1)
It is listed on page 41.

The crosslinked copolymer to be made porous in the method of the present invention needs to have a specific porous structure. That is, the copolymer needs to have a specific surface area of 100 m2/g or more, a pore volume of 0.2 ml/g or more, and an average pore radius of 10 nm or more.
If the average pore radius is smaller than 10 nm, the specific adsorption substance will not diffuse sufficiently and the elubility effect will not be achieved. A porous copolymer having such physical properties can be produced by appropriately selecting the reaction conditions of the above-mentioned known method.

In the method of the present invention, porosity is improved by allowing a Lewis acid catalyst to act on the crosslinked copolymer, and such Lewis acid catalysts include aluminum chloride, ferric chloride, boron trifluoride, Aprotic catalysts active in the Friedel-Crafts reaction, which are made of metal halides such as zinc chloride, titanium tetrachloride, stannic chloride, and aluminum bromide, are useful.

The amount of Lewis acid catalyst used varies depending on the desired porosity to be imparted to the crosslinked copolymer and the activity of the catalyst used, but is generally 0.05 to 1 g per 1 g of the crosslinked copolymer.
The amount may be determined as appropriate within the range of 1.0 g.

When treating a crosslinked copolymer with a Lewis acid catalyst according to the present invention, it is generally necessary to treat the crosslinked copolymer in the presence of an organic solvent that is inert in the system, particularly an organic solvent that is inert to the reaction that will cause the crosslinked copolymer to swell well. Preferably, the treatment is carried out. Such solvents include nitromethane, nitrobenzene, dichloroethane,
Examples include 0-dichlorobenzene.

The amount of the swelling solvent to be used may be an amount sufficient to sufficiently swell the crosslinked copolymer and carry out the reaction, and is generally used in the range of 1 ml to 10 ml per 1 g of the crosslinked copolymer.

Treatment of crosslinked copolymers with Lewis acid catalysts is generally carried out at 0°C.
It is carried out for 1 to 20 hours at ~80°C. After treatment with a Lewis acid catalyst, water, hydrochloric acid water, or alkaline water is added to the reaction system to eliminate the activity of the Lewis acid as a Friedel-Crafts catalyst, and the hydrolysis of the Lewis acid catalyst is carried out on the aqueous layer side. The reaction can be stopped by extracting the material. The swelling solvent can be removed from the crosslinked copolymer by placing the crosslinked copolymer in water and azeotropically distilling it off, or by washing it with a water-soluble organic solvent such as acetone or methanol and then washing it with water. be able to. The reason why the crosslinked aromatic copolymer becomes porous due to the treatment with a Lewis acid catalyst is unknown, but the crosslinked aromatic copolymer is treated with a Lewis acid catalyst while being swollen with a swelling solvent. It is presumed that this causes cleavage of crosslinks and realkylation in the swollen state, resulting in porosity.

The porous crosslinked copolymer thus obtained can be used as a synthetic adsorbent, and can also be converted into an ion exchange resin or chelate resin by sulfonation or chloromethylation and subsequent amination.

Furthermore, when the porous crosslinked copolymer obtained by the method of the present invention is used as an adsorbent, an appropriate solvent is selected and used for elution of the adsorbed substance from the adsorbent, but The selection is made in consideration of the molecular weight, chemical structure, chemical stability, etc. of the substance to be adsorbed. In general, when selecting a solvent for the elution process, it is preferable to use a solvent that strongly promotes the solubility of the adsorbed substance compared to the solvent used in the adsorption process of the adsorbed substance. It will be done. Examples of these solvents include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, methyl alcohol, and amyl alcohol, ketones such as acetone and methyl isophthyl ketone, and organic solvents such as acetonitrile. Furthermore, various buffer solutions, acidic solutions, and alkaline solutions that act on the ionic dissociative groups of the adsorbed substance are used; specifically, acetic acid buffer solutions, phosphate buffer solutions, hydrochloric acid solutions, sulfuric acid solutions, and sodium hydroxide. Examples include solutions, aqueous ammonia solutions, and the like. These eluants can be used alone or in combination, but can also be used sequentially depending on the case.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples.

In the examples, pore physical properties such as specific surface area were determined by the B, E, T method using nitrogen adsorption.

Example 1 Diaion HP 20 (Mitsubishi Kasei Corporation registered trademark;
Styrene-'; hinylbenzene cross-linked copolymer: Pore volume 1.3 ml/g Specific surface area 600 m2/g Average pore radius 25 nm) 20 g (dry product) was placed in a four-bottle flask equipped with a stirrer and placed in a container. Replace the inside with nitrogen,
A further 100 ml of ethane dichloride was added. Stirring was continued at room temperature to sufficiently swell the crosslinked copolymer with the solvent. After 1 hour, 10 g of iron chloride was quickly added. After confirming that the iron chloride was uniformly dispersed, the temperature of the reactor was increased to 80℃.
It was set to °C.

After continuing stirring for 6 hours, it was cooled to room temperature. After the reaction, 100 ml of water was added and after stirring at room temperature for 4 hours, the crosslinked copolymer was filtered, and the crosslinked copolymer was transferred to a column and washed sequentially with 500 ml of acetone, 500 ml of methanol, and 500 ml of water to obtain 78 ml of crosslinked material. A copolymer was obtained. The obtained resin was designated as Sample A, and its physical properties are shown in Table 2.

Example 2 Specific surface area 550 m2/g, pore volume 1.0 ml/
g. The reaction was carried out in the same manner as in Example 1, except that a styrene-divinylbenzene crosslinked copolymer (degree of crosslinking: 20%) with an average pore radius of 50 nm or more was used, and nitrobenzene was used instead of ethane dichloride as the swelling solvent. was carried out.

The obtained resin was designated as Sample B, and its physical properties are shown in Table 2.

Comparative Example 1 Specific surface area 600 m2/g, pore volume 0.9 ml/
The reaction was carried out in the same manner as in Example 1, except that a styrene-divinylbenzene crosslinked copolymer (degree of crosslinking: 30%) having an average pore radius of 8 nm was used. The obtained resin was designated as Sample C, and its physical properties are shown in Table 2.

Reference Example 1 Adsorption and desorption tests were conducted on the obtained samples A, B, and C using standard substances.

(Adsorption and elution test of cephalosporin C) 4000p of cephalosporin C was added to the column filled with each sample.
pm aqueous solution (pH adjusted to 2.5 with hydrochloric acid) was passed through the column until the column outlet concentration reached 2000 ppm. Next, an eluent (aqueous solution with pH = 8.5) was passed through the column adsorbing cephalosporin C, and the concentration of eluted cephalosporin C was checked over time. The amount of sporin C was measured.

Table 1 Comparison of elubility of each resin Since it can adsorb and elute substances in a short time, it is effectively used in the field of purification of pharmaceuticals, foods, etc.

Claims (1)

[Claims] (1) Specific surface area 100m^2/g or more, pore volume 0.2
ml/g or more and an average pore radius of 10 nm or more, a porous resin characterized in that a Lewis acid catalyst is applied to a crosslinked copolymer of an aromatic addition polymerizable monomer in the presence of an inert organic solvent. Production method.