Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-06-15
2003-11-11
Wilson, D. R. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S295000, C525S327100, C524S269000, C524S548000, C560S209000, C568S867000
Reexamination Certificate
active
06646083
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a crosslinked polymer as well as a method of producing the same and a method of using the same. More particularly, it relates to a crosslinked polymer suited for use as an ion exchange resin or a polymer catalyst, a crosslinking agent suited for use in producing crosslinked polymers, a method of producing crosslinked polymers, a method of producing a spherical particle suited for use in producing crosslinked polymers, a method of using crosslinked polymers, a method of producing a hydroxy alkyl (meth)acrylate and a method of producing glycols using crosslinked polymers.
BACKGROUND ART
Crosslinked polymers having strong basicity or like properties can show ion exchange activity and/or catalytic activity in various reactions and therefore are used widely as ion exchange resins or polymer catalysts in various fields of industry, for example in pure water production, amino acid separation and purification, catalyst recovery, metal recovery, iodine recovery, sugar solution recovery, sucrose decolorization, uranium purification, and formalin purification. Strongly basic styrenic ion exchange resins, which are copolymers of styrene and divinylbenzene, for instance, are generally known as such crosslinked polymers.
Such strongly basic styrenic ion exchange resins are generally produced by suspension polymerizing styrene and divinylbenzene to thereby synthesize a crosslinked poly-styrene-divinylbenzene, which is a crosslinking product derived from a styrene-divinylbenzene copolymer, in a spherical form, then chloromethylating this crosslinked polymer using a Lewis acid, for instance, and causing a tertiary amine or the like to add thereto to thereby introduce an amine structure thereinto. Such strongly basic ion exchange resins can be involved in ion exchange reactions in the whole pH range and therefore are utilized in a wide range of applications.
In such strongly basic ion exchange resins, the nitrogen atom in the amine structure resulting from introduction of a tertiary amine or the like into the crosslinked polymer, namely the nitrogen atom in the tertiary amine-derived quaternary ammonium salt (OH form), is the main site contributing to the ion exchange capacity or catalytic activity. For strongly basic crosslinked polymers, it is therefore very important that such sites, namely the so-called active sites, are retained stably so that the function thereof can be performed continuously with good durability. However, when strongly basic styrenic ion exchange resins are used at an elevated temperature not lower than 40° C., a problem is encountered, namely insufficient resistance to thermal degradation as a result of elimination or decomposition of the amine structure due to ready thermal decomposability of the quaternary ammonium salt from the chemical structure viewpoint, which leads to a reduction in performance.
To cope with such a problem, it is a current practice to render the amine structure less eliminable by selecting a chloromethylating agent as a spacer or increase the molecular weight of the resin to thereby increase the introduction of the amine structure in excess of a certain level. Essentially, however, these measures cannot render the quaternary ammonium salt resistant to thermal decomposition, hence cannot improve the resistance of strongly basic ion exchange resins to thermal decomposition to a satisfactory extent. Therefore, the advent of a technology has been awaited by which the active sites contributing to the ion exchange capacity or catalytic activity can be essentially rendered resistant to thermal decomposition and by which crosslinked polymers widely usable in various applications as strongly basic ion exchange resins, for instance, and a method of producing the same can be developed and established.
Meanwhile, if a crosslinked polymer is obtained in the form of spherical particles, that form will provide an increased surface area and improve the handling qualities of the polymer and, thus, it becomes possible to use the same widely in various industrial products. As examples of the products which utilize a crosslinked polymer in the form of spherical particles, there may be mentioned ion exchange resins, water absorbing resins and catalysts, among others. Not only such organic spherical particles but also inorganic spherical particles such as spherical silica gel particles are of commercial importance, and methods of producing such spherical particles have also been the targets of investigation.
A simple and easy method of producing a spherical particle comprises, for example, dispersing in a medium or formation of a dispersed product by polymer formation in a medium, and this method is suited for the formation of spherical particles uniform in shape and size, hence is widely employed on commercial scales. However, when the spherical particles formed as a dispersed product tend to coagulate or stick together, there arises a problem: they give agglomerate bodies, hence no uniform products can be obtained. Therefore, in producing spherical particles in a medium, the spherical particles formed are prevented from giving agglomerate bodies by using a suspending agent or carrying out vigorous stirring. In some cases, however, such means fail to give sufficiently uniform spherical particles or cannot be applied to the production of high quality commercial products since the use of a suspending agent or vigorous stirring is required. Further, there is still room for improvement from the production cost viewpoint.
Japanese Kokai Publication Hei-04-311710 discloses a method of preparing homopolymers or copolymers by preparing a two-phase system containing droplets of an aqueous solution of at least one water-soluble monomer such as a diallyldialkylammonium chloride and carrying out the polymerization in the presence of a combination of a precipitation inhibitor and an emulsifier. This method of preparation was thought to give spherical particles uniform to some extent with a slight particle size distribution. However, the combined use of a precipitation inhibitor and an emulsifier for preventing spherical particles from becoming agglomerate bodies cannot be applied to the production of high quality commercial products in some cases and, in view of the use of these additives, there is room for improvement from the production cost viewpoint.
Japanese Kokoku Publication Hei-02-41528 discloses a method of producing spherical ion exchange resins which comprises using a copolymer having a hydrophilic group and a hydrophobic group as a dispersing agent in producing copolymers following suspending an aqueous solution containing a diallyldialkylammonium chloride and a compound having at least two diallylammonium groups in each molecule or a compound having at least two para-(or meta-)vinylphenylmethylammonium groups or their mixture in each molecule in a water-insoluble organic solvent. This production method, too, was considered to be able to give spherical particles uniform to some extent. However, this production method, too, uses such a copolymer as a dispersing agent and, therefore, cannot be applied to the production of high quality commercial products in certain cases and there is also room for improvement from the production cost viewpoint.
As mentioned above, investigations have been made to develop crosslinked polymers and establish a method of producing the same. If such crosslinked polymers can be used as a catalyst with commercial advantage, then it will become possible to produce various chemical products efficiently and expediently. Accordingly, investigations are being made concerning how to use such crosslinked polymers.
For instance, glycols can be produced commercially by reacting an oxirane compound with water and, in the production of monoethylene glycol, which is industrially of particular importance as a glycol, monoethylene glycol is selectively produced as the main product by using a large amount of water to thereby prevent the formation of byproducts, such as diethylene glycol and triethylene glycol
Hirano Yoshiaki
Kubo Takafumi
Morita Takehiko
Sugiyama Yutaka
Takematsu Kenichi
Connolly Bove & Lodge & Hutz LLP
Nippon Shokubai Co. , Ltd.
Wilson D. R.
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