Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Nitrogen-containing reactant
Reexamination Certificate
2001-01-30
2002-09-17
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Nitrogen-containing reactant
C528S422000
Reexamination Certificate
active
06451961
ABSTRACT:
The present invention relates to an ethylenimine polymer, an aqueous solution of an ethylenimine polymer, a production process for the same and a purifying process therefor.
It is publicly known that monoethanolamine is subjected to intermolecular dehydration reaction in the presence of a catalyst to obtain ethylenimine. Known as the catalyst are, for example, tantalum base catalysts (U.S. Pat. Nos. 4,289,656, 4,337,175 and 4,477,591), silicon-alkaline metal and/or alkaline earth metal base catalysts (Japanese Patent Publications No. 13699/1993 and 13700/1993), phosphorus-alkaline metal and/or alkaline earth metal base catalysts (Japanese Patent Publications No. 76344/1993, 87301/1993, 76343/1993, 55498/1993 and 16905/1993), and catalysts prepared by carrying these silicon/phosphorus-alkaline metal/alkaline earth metal base catalyst compositions on molded ceramic carriers (Japanese Patents Laid-Opens No. 132564/1997 and 194455/1997).
A part of these catalysts is used for producing ethylenimine in an industrial scale, and an ethylenimine-containing reaction mixture obtained in this reaction is purified through a high degree purifying step and then used for synthesizing various ethylenimine polymers. To be specific, contained in an ethylenimine-containing reaction mixture obtained by intermolecular dehydration reaction of monoethanolamine are, in addition to intended ethylenimine, unreacted monoethanolamine; oligomers of ethylenimine; aldehydes such as acetaldehyde; heavy impurities such as a Schiff base produced by a reaction of acetaldehyde with monoethanolamine of the raw material; lower amines such as ammonia, methylamine and ethylamine; and acetonitrile. Accordingly, it is recognized that these impurities have to be removed from the above ethylenimine-containing reaction mixture through a high degree purifying step in order to obtain purified ethylenimine which can be used for polymerization reaction.
In conventional techniques, ethylenimine which is purified to such a high degree and therefore is expensive has to be used to produce an ethylenimine polymer, so that the production cost thereof can not be avoided from going up, and they are not necessarily industrially advantageous.
Accordingly, an object of the present invention is to provide an ethylenimine polymer which solves the problems described above on the conventional techniques and which is decreased in a production cost and industrially advantageous, and a production process for the same.
The present inventors have found that an ethylenimine polymer having a performance which is entirely equivalent to those of conventional ethylenimine polymers obtained by using purified ethylenimine for a raw material can be produced by polymerizing crude ethylenimine obtained by a simple distilling operation from an ethylenimine-containing reaction mixture produced by subjecting ethanolamine to intermolecular dehydration reaction, particularly crude ethylenimine having impurity contents which are controlled in specific ranges, and they have come to complete the present invention based on this knowledge.
Thus, according to the present invention, provided is an ethylenimine polymer characterized by being produced by polymerizing crude ethylenimine obtained by intermolecular dehydration reaction of monoethanolamine in the presence of a catalyst.
Further, according to the present invention, provided is a production process for an ethylenimine polymer characterized by subjecting monoethanolamine to intermolecular dehydration reaction in the presence of a catalyst to produce crude ethylenimine and then polymerizing this crude ethylenimine.
A process itself for producing an ethylenimine polymer by subjecting monoethanolamine to intermolecular dehydration reaction in the presence of a catalyst to produce an ethylenimine-containing reaction mixture shall not specifically be restricted and can be carried out by a usually well known process. To be specific, vaporized monoethanolamine is introduced into a catalyst layer as a raw material gas, if necessary, after suitably diluting this with inert gas such as nitrogen or after adding thereto ammonia, steam or hydrogen for the purpose to inhibit side reactions. The reaction pressure may be any of atmospheric pressure, reduced pressure and elevated pressure. The reaction temperature falls usually in a range of 300 to 500° C. A space velocity of the raw material gas is varied depending on a concentration of monoethanolamine and the kind of the catalyst used and therefore can not absolutely be specified, and it falls usually in a range of 50 to 5000 h
−1
. The catalyst to be used shall not specifically be restricted as well, and the catalysts described in the above patent publications can be used. Among them, suitably used are catalysts described in Japanese Patent Publications No. 13699/1993, 13700/1993, 76344/1993, 87301/1993, 76343/1993, 55498/1993 and 16905/1993.
The ethylenimine-containing reaction mixture obtained by the gas phase intermolecular dehydration reaction described above is collected by means of a scavenger or condensed as it is and collected. An amine compound is suited as the scavenger, and particularly monoethanolamine is the most preferable since it is also the raw material. Mainly ethylenimine, unreacted monoethanolamine and moisture are contained in the ethylenimine-containing reaction mixture. Contained as by-products are lower amines such as ammonia, methylamine and ethylamine; acetonitrile; aldehydes such as acetaldehyde; Schiff bases produced by a reaction of acetaldehyde with monoethanolamine which is the raw material.
In the present invention, preferably produced is an ethylenimine polymer by polymerizing crude ethylenimine which is obtained by subjecting the ethylenimine-containing reaction mixture described above to a simple distilling operation and in which impurity contents are controlled in specific ranges. Such crude ethylenimine contains, for example, 90% by weight or more, preferably 95 to 99.9% by weight of ethylenimine, and as impurities, less than 1000 ppm (by weight), preferably less than 500 ppm of monoethanolamine, less than 2% by weight, preferably less than 1% by weight in total of lower amines comprising ammonia, methylamine and ethylamine, less than 2% by weight, preferably less than 1% by weight of acetonitrile and less than 1000 ppm (by weight) of water.
In addition to the above, the ethylenimine-containing reaction mixture is brought into contact with an organic solvent such as toluene and xylene to extract heavy matters contained in the reaction mixture, whereby such crude ethylenimine as described above can be obtained as well.
Crude ethylenimine having an ethylenimine content of smaller than 90% by weight and impurity contents exceeding the ranges described above causes the problem that an ethylenimine polymer obtained by polymerization thereof is inferior in performances, and therefore it is not preferred in the present invention.
In the present invention, such crude ethylenimine as described above is recovered from the ethylenimine-containing reaction mixture by a simple distilling operation or extracting operation, and then this crude ethylenimine is polymerized to produce an ethylenimine polymer.
A process for producing an ethylenimine polymer using crude ethylenimine shall not specifically be restricted, and it can be produced by a process usually used for producing an ethylenimine polymer. The polymerization catalyst and the polymerization conditions can suitably be selected from those usually used for polymerizing ethylenimine. For example, crude ethylenimine can be reacted in the presence of an effective amount of an acid catalyst, for example, hydrochloric acid at 0 to 200° C. (Japanese Patent Publication No. 33120/1074, Japanese Patent Publication (through PCT) No. 501757/2000 and the like). Further, crude ethylenimine may be addition-polymerized on the basis of an ethylenimine polymer. The ethylenimine polymer of the present invention includes an ethylenimine homopolymer and a copolymer of ethylenimine with a compound copolyme
Onda Yoshiyuki
Satoh Isao
Suzuki Seiichi
Hampton-Hightower P.
Nippon Shokubai Co Ltd
Sherman & Shalloway
LandOfFree
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