Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant which is a cellular material derived from...
Reexamination Certificate
2003-02-26
2004-12-14
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant which is a cellular material derived from...
C526S209000, C526S216000, C526S217000, C526S226000, C526S303100, C526S307100, C526S317100, C526S319000
Reexamination Certificate
active
06831144
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anionic polymerization process of polymerizing an anionic polymerizable monomer with an anionic polymerization initiator, and a process for producing a polymer using this polymerization process.
2. Related Art of the Invention
Various investigations have been made on a process of subjecting a polar monomer such as a methacrylic acid ester or an acrylic acid ester to anionic polymerization. However, such a polar monomer has a moiety which receives nucleophilic attack easily, such as a carbonyl group. Upon anionic polymerization for the polar monomer, therefore, it is relatively difficult that a high living polymerization property is exhibited since there arises a side reaction of the monomer or an intermolecular cyclization reaction (so-called back biting) at the growing terminal of the resultant polymer.
It is suggested that when a polar monomer is subjected to anionic polymerization using an organolithium compound as a polymerization initiator, an organoaluminum compound is caused to be present in the polymerization system. According to this manner, the organoaluminum compound coordinates to the growing terminal. Thus, the growing terminal can be stabilized so that its nucleophilicity can be lowered. As a result, it appears that the living polymerization property upon the polymerization can be raised. As processes for performing anionic polymerization of a polar monomer in the presence of an organoaluminum compound, using an organolithium compound as a polymerization initiator, the following processes (1)-(6) are reported:
(1) a process of performing a polymerization reaction of a methacrylic acid ester in the presence of an organoaluminum compound such as trialkylaluminum or dialkyl(diphenylamino)aluminum in an aromatic hydrocarbon solvent, using t-butyllithium as a polymerization initiator (JP-B-H7-57766),
(2) a process of polymerizing a methacrylic acid ester in the presence of a specific organoaluminum compound having one or more bulky groups (for example, triisobutylaluminum or diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum) in a hydrocarbon solvent, using an organolithium compound such as t-butyllithium as a polymerization initiator (U.S. Pat. No. 5,180,799),
(3) a process of polymerizing methyl methacrylate in the presence of an organoaluminum compound, such as methylbis(2,6-di-t-butylphenoxy)aluminum, ethylbis(2,6-di-t-butylphenoxy)aluminum, isobutylbis(2,6-di-t-butylphenoxy)aluminum or tris(2,6-di-t-butylphenoxy)aluminum, in an aromatic hydrocarbon solvent, using an organolithium compound as a polymerization initiator (U.S. Pat. No. 5,656,704),
(4) a process of polymerizing a methacrylic acid ester or an acrylic acid ester in the presence of methylbis(2,6-di-t-butylphenoxy)aluminum or ethylbis(2,6-di-t-butylphenoxy)aluminum in toluene, using t-butyllithium as a polymerization initiator (Polymer Preprints, Japan, Vol. 46, No. 7, pp. 1081-1082 (1997) and Polymer Preprints, Japan, Vol. 47, No. 2, p. 179 (1998)),
(5) a process of polymerizing methyl methacrylate in the presence of trialkylaluminum in toluene, using t-butyllithium as a polymerization initiator (Makromol. Chem., Supplement. Vol. 15, pp. 167-185 (1989)), and
(6) a process of polymerizing methyl methacrylate in the presence of diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum in toluene, using t-butyllithium as a polymerization initiator (Macromolecules, Vol. 25, pp. 5907-5913 (1992)).
Furthermore, it is reported that when a polar monomer is subjected to anionic polymerization in the presence of an organoaluminum compound using an organolithium compound as a polymerization initiator, a certain additive is caused to be present in the polymerization system so that the rate of the polymerization can be increased or so that uniformity of the polymerization is improved and the molecular weight distribution of the resultant polymer can be narrowed. Such reports are, for example, about the processes (7) and (8).
(7) When a methacrylic acid ester is polymerized in the presence of trialkylaluminum in toluene using t-butyllithium as a polymerization initiator, the rate of the polymerization is improved and the molecular weight distribution of the resultant polymer is narrowed by adding to the polymerization system an ester compound, such as methyl pivalate or diisooctyl phthalate, in an amount of about 10% by weight of toluene (solvent). In the case in which a crown ether such as 12-crown-4 is added instead of the ester compound, the same improvement effects are exhibited. However, in the case in which tetrahydrofuran, 1,2-dimethoxyethane, N-methylpyrrolidine or the like is caused to be present instead of the ester compound, the improvement effects are not exhibited (Macromolecules, Vol. 31, pp. 573-577 (1998)).
(8) When a methacrylic acid ester or an acrylic acid ester is polymerized in the presence of an organoaluminum compound such as trialkylaluminum in a hydrocarbon solvent using an organolithium compound such as ethyl &agr;-lithioisobutyrate or t-butyllithium as a polymerization initiator, the rate of the polymerization is improved and the molecular weight distribution of the resultant polymer is narrowed by adding to the polymerization system an ether compound such as triethylene glycol dimethyl ether (triglyme), dimethoxyethane or crown ether, or an organoquaternary salt such as tetraalkylammonium halide or tetraphenylphosphonium halide (International publication: WO98/23651).
As described as the above-mentioned processes (1)-(8), various suggestions are made on processes of anionic polymerization of a polar monomer in the presence of an organolithium compound and an organoaluminum compound. However, the polymerization initiators that are actually used in these processes are limited to specific compounds such as t-butyllithium and ethyl &agr;-lithioisobutyrate. This would be because it is considered that a high polymerization initiation efficiency and a high polymerization rate can be attained. However, t-butyllithium has mighty self-ignition ability, and has problems about safety thereof and handling performances upon transportation, storage and the like. Concerning ethyl &agr;-lithioisobutyrate, an operation for synthesizing it and a subsequent purifying operation are complicated. For these reasons, it is difficult to say that these polymerization initiators, which make it possible to attain a high polymerization initiation efficiency and a high polymerization rate, are suitable for use in an industrial scale. Besides, examples of specific experiments reported as the processes (1)-(8) include examples wherein polymerization initiation efficiency is insufficient for practical use.
In the case in which a polar monomer such as a methacrylic acid ester or an acrylic acid ester is block-copolymerized with another monomer, a living polymer resulting from the polymerization of the one monomer needs to have such a high living polymerization property that causes the polymerization of the other monomer to start. However, in order to exhibit such a high living polymerization property upon anionic polymerization in the presence of an organolithium compound and an organoaluminum compound, it is necessary in many cases to set the temperature upon the polymerization to a very low temperature, for example, about −60° C. In such polymerization operation at a very low temperature, many facilities become necessary for cooling. Thus, industrial adoption of this operation is disadvantageous. Moreover, in the case in which an ester of a primary alcohol and acrylic acid, such as n-butyl acrylate, is used as the polar monomer upon polymerization, the living polymerization property upon the polymerization becomes especially low. By the inventors' investigations, the following results were obtained: when an ester of a primary alcohol and acrylic acid was polymerized in a reaction system in the presence of trialkylaluminum and a crown ether or an organoquaternary salt as reported as the process (8) at a very low temperature of ab
Hamada Kenichi
Ishiura Kazushige
Kato Masaji
Yaginuma Sachie
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Zalukaeva Tatyana
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