Note: Descriptions are shown in the official language in which they were submitted.
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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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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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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
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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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_ 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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(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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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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