CA1142298A - Method of manufacture of ion exchange resins - Google Patents

Abstract

- i -PATENT APPLICATION OF
Hiroshi Akiyama and Koji Oinuma for METHOD OF MANUFACTURE OF ION EXCHANGE RESINS
Abstract of the Disclosure A method for the manufacture of an ion exchange resin having a granular activated carbon as the matrix thereof, comprises causing a granular activated carbon to retain therein up to about 30% by weight, based on the weight of granular activated carbon, of a polymerizable solution containing monovinyl monomers and/or polyvinyl monomers in the presence of a polymerization initiator and, optionally, an organic solvent, and allowing the mixed solution as retained in the granular activated carbon to undergo polymerization in an aqueous medium and subsequently introducing therein an ion exchange group.

Description

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METHOD OF MANUFACTURE OF ION EXCHANGE RESINS
Background of the Invention This invention relates to a method for the manu-facture of ion exchange resins and more specifically to a method for the manufacture of ion exchange resins having a granular activated carbon as the matrix thereof.
Generally, ion exchange resins formed of monovinyl monomers or polyvinyl monomers, particularly those based on styrene J come in particle diameters usually ranging from 50 mesh (0.297 mm) to 16 mesh (1.19 mm).
They are produced` by first preparing granular copolymers through dispersion polymerization and introducing ion exchange groups into the resultant copolymers. Accord-ing to this method of polymerization, the largest ;
possible particle diameter in which the granular co- :
polymers are obtained is about 14 mesh (1.41 mm). Re-cently, ion exchange resins referred to as "giant resins" have been prepared and have particle diameters of from 30 mesh (0.59 mm) to 16 mesh (1.19 mm). It is now, however, desirable to provide ion exchange resins having an even greater particle size diameter.
Various ion exchange resins of large particle -diameters based on monovinyl monomers and/or polyvinyl ` monomers are disclosed in Japanese Patent Publication No. 4144/1957. A review of the publication, howe~er, reveals that the methods taught therein are not able to readily produce ion exchange resins of uniform particle size diameters in a commercial quantity.

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- 2 -An object of this invention, therefore, is to provide a method for producing an ion exchange resin of a large, uniform particle diameter in commercially utilizable quantities.
DETAILED DESCRIPTION
This invention relates to a method for preparing ion exchange resins comprising the steps of treating a granular activated carbon with a mixed solution con-taining monovinyl monomers and/or polyvinyl monomers in the presence of a polymerization initiator, allowing the mixed solution which is thereby retained in the granular activated carbon matrix to undergo polymeri-zation and thereafter introducing a functional group onto the polymer or copolymer.
The ion exchange resin according to the present invention, combines the properties of a granular acti-vated carbon and that of a synthetic ion exchange resin.
The ion exchange resin prepared according to this in-vention has a uniform appearance and exhibits excellent structural stability.
A key feature of the ion exchange resins of this invention resides in the fact that the granular acti-vated carbon retains, in the interstices thereof, the polymer formed from monovinyl monomers and/or poly-vinyl monomers. This retention of the polymer is accom-plished by causing the granular activated carbon to retain therein the mixed solution containing the mono-vinyl monomers and/or polyvinyl monomers and allowing the mixture, as retained in the granular activated carbon, to undergo polymerization.
It is important, however, that the amount of the monomer(s) to be retained in the granular activated carbon should not exceed 30% by weight of the weight of the granular activated carbon. If more than 30% by weight of the monomer(s) are retained, then the re-sultant product of the polymerization may suffer from . .

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~structural collapse when contacted with swell~ng sol-vents. Swelling solvents are commonly encountered when functionalizing the polymer-activated carbon composition according to methods well known in the art.
The retention of the polymer in the granular activated carbon may be accomplished by immersing the granular activated carbon in the monomer solution.
Additionally, the granular activated carbon may be dis-persed in water or in an aqueous solution of a dispersant ~ followed by addition of the monomers to the resultant dispersion, thereby allowing the carbon granules to absorb the monomer from the dispersion. This method is particularly advantageous when it is desired to add a small quantity of vinyl monomers to be uniformly dis-tributed in granular activated carbon.
The granular activated carbon to be used as the matrix for the ioh exchange resins of this invention may consist of a variety of forms. Selection of the granular activated carbon depends on the purpose for which the ion ~o exchange resin finally produced is used.
One type of organic solvent which may be used can possess an ability to swell the polymer to be formed within the granular activated carbon. Examples of such organic solvents which are good swelling solvents for the resultant polymer include benzene, toluene, xylene, ethylene dichloride, trichloroethylene and such o~gan~c solvents having a linear polymer dissolved in advance therein.
Alternatively, there may be used an organic solvent in which the monomer is soluble but which is a poor swell-ing solvent for the resultant polymer. Examples of suchorganic solvents include methyl isobutyl carbinol, n-hexane, t-amyl alcohol and butanol.
The polymerization may be performed in an aqueous solution system as the polymerization temperature can be easily controlled. A dispersant may also be used as part of the aqueous polymerization system. The amount . ~

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11422~8 of aqueous polymerization solution used may vary widely although it is preferred that the weight be three to four times the weight of the granular activated carbon.
Examples of monovinyl monomers which may be used in practicing this invention include aromatic monovinyl monomers such as styrene, methylstyrene, ethylstyrene, and chlorostyrene and the like and aliphatic monovinyl monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and ~ butyl methacrylate and the like.
Examples of polyvinyl monomers which may be used in practicing this invention include aromatic monomers such as divinyl benzene, divinyl naphthalene and trivinyl benzene and the like and aliphatic monomers such as ethylene glycol diacrylate, ethylene glycol dimethacry-late and divinyl adipate and the like.
Generally in the polymerization, a polymerization initiator is used for the purpose of causing the re-action to proceed to completion. The polymerization ~o initiator for the present invention may be selected from among polymerization initiators which are known to one skilled in the art. Examples of such polymeri-zation initiators include benzoyl peroxide, tertiary butyl peroxide, lauroyl peroxide, and azobisisobutyroni-trile and the like. Other polymerization initiators which are well known to those skilled in the art may also be used.
The polymerization temperature may vary widely.
However, the polymerization temperature should be higher than the decomposition temperature of the polymeriza-tion initiator used. Under normal pressure, for example, the polymerization is carried out at a tem-perature in the range of from about 50C. to about 90C .
After polymerization within the activated carbon ~ .
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-matrix, a functional ion exchange group may be incor-.
porated onto the polymer in any suitable manner known in the art. One of the conventionally known methods of functionalizing is as follows. Sulfuric acid, chlorosulfonic acid or sulfur trioxide may be used for sulfonating an aromatic resin in the presence of an organic solvent capable of swelling an inner polymer to produce a cation exchange resin.
An anion exchange resin may be obtained by halo-1 methylating the resin with chloromethyl ether or hydro-chloric acid, methanol and formalin and the like and subsequently aminating the halomethylation product with an amine such as, for example, trimethyl amine, diethyl-ethanol amine, ethylene diamine or diethylene triamine and the like.
The ion exchange resin of this invention, which is obtained by using the granular activated carbon as the matrix as described above, is uniform and capable of commercial production. The resin of this invention 2~ combines the characteristic properties inherent in any synthetic ion exchange resin and the properties of activated carbon. These ion exchange resins may be used in a variety of commercial applications.
In order to more fully illustrate the nature of this invention and the manner of practicing the same, the following examples are presented.
Example 1.
A 70-9. portion of a commercially available granular activated carbon (6 to 8 mesh in particle diameter, manu-

3~ factured by Japan Carbon Co., Ltd. and marketed under the-trademark "Columbian) is allowed to absorb styrene, di-vinyl benzene (58% in purity) and azobisisobutyronitrile (as a polymerization initiator) in varying amounts indi-cated in Table 1 below. The imbibed granular activated carbon is stirred in 300 g. of water at 70C. for four `' Ç~
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114Z~8 hours and then heated to 75 to 80C. for one hour.
After completion of the reaction, the impregnated carbon is drained and air-dried at 80C. for five hours.

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11~2298 _ Table 1 Divinyl Azobisis-Product Styrene Benzene butyron-No. (g) _ (g) _ itrile ~g)Yield (g) 1 6 1 0.10 75.6 2 12 2 0.14 80.5 3 18 3 0.21 88.9 *4 60 10 0.7 108 *Product No. 4 is a control wherein the amount ofmonomers used and retained in the activated carbon matrix exceeds 30% by weight of the activated carbon used.
(A) Strong Acid Resin To a 20-g. portion of each product of Table 1 ~`
is added, with stirring, 10 9. of ethylene dichloride and 200 9. of 98% concentrated sulfuric acid. The m~xture is sulfonated at 120C. for four hours. Upon completion of the sulfonation, the reaction mixture is thoroughly washed with water and neutralized with 10% caustic soda.
The properties of the resultant cation exchange resins are shown in Table 2.
Table 2 Ion Exch. %
ProductCapacity Bead Cracked No. (meq/g) A~pearance Beads Yield ~g) 1 0.18 No cracks 0 24.8 2 0.20 " " 0 24.6 3 0.27 " " 0 26.3

4(control) 0.45 Cracks 52 25.3 formed ::
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2~9~3 (B) Strong Base Resin In a flask, a 20-g. portion of each product of Table 1 is thoroughly stirred with 100 g. of ethylene dichloride and 50 9. of chloromethyl ether for 30 minutes. To the resultant mixture is added 10 g. of anhydrous zinc chloride and the mixture is heated at 45C. for seven hours. Upon completion of the chloro-methylation, the reaction mixture is treated with water to decompose the excess chloromethyl ether and then washed thoroughly with water. To the washed reaction mixture is added, with stirring, 20 g. of aqueous 30%
trimethyl amine. The mixture is held at 50C. for one hour and then heated to remove the ethylene dichloride (EDC) and excess trimethyl amine. The properties of the resultant resins are shown below.
Table 3 Ion Exch. Water Bead ~ -Product Capacity Content Appear- Cracked Yield No. (meq/g) (%) ance Beads (g) 1 0.11 40.5 No cracks 0 21.2 2 0.19 39.3 " " 0 23.4 3 0.26 43.6 " " 0 25.9 4(control) 0.35 48.7 Cracks 38 28.5 formed .

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: , ' -``` ~1~2298 Example 2:
A 70-g. portion of the same granular activated carbon used in Example 1 is allowed to absorb a solution consisting of 12 g. of styrene, 2 g. of divinyl benzene, 10 g. of methyl isobutyl-carbinol and 0.34 g. of azo-isobutyronitrile. The resultant monomer-retaining granular activated carbon is then stirred in 300 g. of an aqueous 2~ sodium chloride solution at 80C. for four hours. It is then heated to remove the methyl isobutyl carbinol from the reaction mixture. Upon removal of the methyl isobutyl carbinol, the reaction mixture is drained and air-dried at 80C. for five hours to yield 82 g. of a polymer-retaining granular activated carbon.
A 20-g. portion of this product is sulfonated by following the procedure of Example l(A). There is consequently obtained a cation exchange resin which is found to possess an ion exchange capacity of 0.25 meq/g, contain no cracks and excel in physical properties.
Although this invention has been described in terms of certain preferred embodiments and illustrated by means of specific examples, the invention is not to be construed as limited except as set forth in the ~ following claims.

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Claims (10)

CLAIMS:

1. An ion exchange resin derived from vinyl monomers and having a functional group therein, said resin being disposed within the matrix of a granular activated carbon particle by polymerization of the vinyl monomers within the matrix of the particle, wherein the ion exchange resin, exclusive of said functional group, comprises up to 30% by weight of said activated carbon particle.

2. An ion exchange resin according to claim 1, wherein said resin is a cationic ion exchange resin.

3. An ion exchange resin according to claim 1 wherein said resin is a sulfonated ion exchange resin.

4. An ion exchange resin according to claim 1 wherein said resin is an anionic ion exchange resin.

5. An ion exchange resin according to claim 1 wherein said resin is an aminated ion exchange resin.

6. A process for preparing an ion exchange resin having a functional group therein and having a granular activated carbon as the matrix thereof comprising dispersing, within the matrix of said carbon, a polymerizable solution containing a polymerization initiator, a polymerizable monomer selected from the class consisting of monovinyl monomers and polyvinyl monomers and mixtures thereof, polymerizing said monomer within said activated carbon matrix and functionalizing the resultant polymer to form an ion exchange resin which, exclusive of said function group, comprises up to 30% by weight of said granular activated carbon.

7. A process according to claim 6 wherein said functional group is a cationic group.

8. A process according to claim 6 wherein said resultant polymer is sulfonated.

9. A process according to claim 6 wherein said functional group is an anionic group.

10. A process according to claim 6 wherein said resultant polymer is aminated.