Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-04-29
2002-06-25
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C521S031000, C521S032000, C521S033000, C525S333400, C525S343000, C525S353000, C525S359100
Reexamination Certificate
active
06410656
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a cation exchanger or chelating agent and a production process thereof. The cation exchanger of the present invention has a novel structure with excellent heat resistance and other features, and the chelating agent of the present invention has a novel structure with excellent chelate forming ability, heat resistance and other features.
BACKGROUND ART
Generally, cation exchange resins are produced by sulfonating styrene-divinylbenzene copolymers with sulfuric acid and/or sulfur trioxide of various concentrations in view of chemical stability of the produced resins, their strength and production cost. There are also known the cation exchange resins produced by introducing a sulfonic group to the terminal of acrylic derivative resins, but these cation exchange resins are poor in chemical stability.
As another exemplification of cation exchange resins, in U.S. Pat. No. 3,944,507 specification, there has been described a cation exchanger incorporated with methylene linkage (benzenesulfonic acid structure), but this cation exchanger is unsatisfactory in heat resistance. There has also been described a cation exchanger produced by introducing a halogen atom into the benzene ring for improving heat resistance, but this cation exchanger has not been commercially produced and used because of liability to ion leakage of its halides such as chlorinated or brominated products.
On the other hand, chelating agents (resins) are the functional resins produced by introducing functional groups capable of forming metal ions and chelates to the crosslinked polymers, and a variety of chelate resins have been proposed according to the type of the chelate-forming functional group used. Typical examples of the chelate-forming functional groups usable for the above purpose are iminodiacetic acid group (—N(CH
2
COO—)
2
) and polyamine group (—NH(CH
2
CH
2
NH)n.H). These chelate resins, for example, the said iminodiacetic acid type chelate resins are usually produced by converting the halogen of a crosslinked polymer containing halogenated methylstyrene into iminodiacetic acid group.
It appears, however, that most of the conventional proposals relating to chelate resins are directed to the improvement of chelate-forming functional groups and no sufficient proposals have been made on the structure between the crosslinked polymer and the chelate-forming functional group.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a cation exchanger which has excellent heat resistance and high reaction rate, is capable of minimized elution from the polymer, and a process for producing such a cation exchanger. Another object of the present invention is to provide a chelating agent of a novel structure having excellent chelate forming ability and heat resistance, and a process for producing such a chelating agent.
DISCLOSURE OF THE INVENTION
An object of the present invention can be attained by a cation exchanger or a chelating agent having at least structural units represented by the following formula (I), the structural units being derived from a crosslinkable monomer containing an unsaturated hydrocarbon group:
wherein A represents a C
3
-C
8
alkylene group or a C
4
-C
9
alkoxymethylene group; L represents SO
3
−
X
+
, where X
+
is a counter ion coordinated with the SO
3
−
group, or a chelate-forming functional group; and the benzene ring may be substituted with an alkyl group or a halogen atom.
Another object of the present invention can be accomplished by a process for producing a cation exchanger as defined in the above first aspect, which comprises suspension-polymerizing at least a precursor monomer having the structural units represented by the following formula (II) and a crosslinkable monomer having an unsaturated hydrocarbon group in the presence of a polymerization initiator, and if necessary introducing a cation exchange group into the obtained spherical crosslinked polymer:
wherein A has the same meaning as defined in the formula (I); Z
1
represents chlorine, bromine, iodine, a hydroxyl group, a tosyl group (toluenesulfonic group), a thiol group or a sulfonic group; and the benzene ring may be substituted with an alkyl group or a halogen atom.
Still another object of the present invention can be achieved by a process for producing a chelating agent as defined in the above first aspect, which comprises suspension-polymerizing at least a precursor monomer having the structural units represented by the following formula (III) and a crosslinkable monomer having an unsaturated hydrocarbon group in the presence of a polymerization initiator, and introducing a chelate-forming functional group into the obtained spherical crosslinked polymer:
wherein A has the same meaning as defined in the formula (I); Z
2
represents chlorine, bromine; iodine or a hydroxyl group; and the benzene ring may be substituted with an alkyl group or a halogen atom.
The present invention is described in detail below.
First, the cation exchanger or chelating agent according to the present invention is explained.
The cation exchanger or chelating agent of the present invention has at least the structural units represented by the above-shown formula (I) and the structural units derived from a crosslinkable monomer having an unsaturated hydrocarbon group.
In case where L in the formula (I) is SO
3
−
X
−
(wherein X
+
is a counter ion coordinated with the SO
3
−
group), a cation exchanger is provided; and in case where L is a chelate-forming functional group, a chelating agent is provided.
L representing a chelate-forming functional group is not specified, and any functional group used in the known chelate resins can be used without restrictions. Typical examples of L include iminodiacetate group (—N(CH
2
COO—)
2
), polyamine group (—NH(CH
2
CH
2
NH)
n
.H), dimethylglycine (dimethylaminoacetate) group (—N
+
(CH
3
)
2
CH
2
COO—) and the like. As compared with, for example, aminomethylsulfonic group disclosed in Japanese Patent KOHYO (Laid-Open PCT Application) No. 4-500223, it is particularly remarkable that these chelate-forming functional groups, are relatively simple in structure, advantageous in cost and also susceptible to the influence of benzene ring because of relatively simple molecular structure, so that the effect by spacer (A) in the present invention, which is described later, is remarkable.
Besides the above-mentioned, there can also be used aminophosphoric group and phosphonic group as the chelate-forming functional group. The aminophosphoric type chelate resins can, for instance, be preferably used for purification of salt water contained in the raw materials of electrolytic sodium hydroxide and are capable of effectively removing the impurities such as calcium and strontium in the salt water. On the other hand, the phosphonic type chelate resins show high adsorptivity for many types of metal ions and have higher selectivity for tri- and tetravalent metal ions than for mono- and divalent metal ions. Because of these properties, the phosphonic chelate resins are advantageously used for selective removal of iron ions in zinc or nickel electroplating solutions and for separation and concentration of uranium and rare earth element ions.
In the formula (I), A represents an alkylene group having 3 to 8 carbon atoms or an alkoxymethylene group having 4 to 9 carbon atoms. Examples of the C
3
-C
8
alkylene groups include propylene, butylene, pentylene, hexylene and octylene, and examples of the C
4
-C
9
alkoxymethylene groups include butoxymethylene and pentoxymethylene. The C
3
-C
8
alkylene groups may be either straight-chain alkylene groups such as mentioned above or branched alkylene groups such as isopropyl and t-butyl groups. When A is an alkylene group, it is preferably a straight-chain alkylene group having 3 to 8 carbon atoms, more preferably the one having 3 to 6 carbon atoms. When A is an alkoxymethylene group, it is preferably the one having 5 to 7 carbon
Jyo Akinori
Kubota Hirohisa
Watanabe Junya
Yano Katsuhiko
Coleman Sudol Sapone P.C.
Lipman Bernard
Mitsubishi Chemical Corporation
Sapone William J.
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