Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-09-18
2003-10-07
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S176000, C526S177000, C526S178000, C526S319000, C526S329700, C525S247000, C525S279000, C525S299000, C525S309000
Reexamination Certificate
active
06630554
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polymerization process giving superior reaction results such as initiation efficiency, comprising an anionic polymerization of a methacrylic ester or an acrylic ester in the presence of a specific organoaluminum compound, using a specific polymerization initiator compound. The present invention also relates to a process for producing a polymer such as a block copolymer, wherein the above-mentioned polymerization process is used.
2. Related Art of the Invention
Not only realization of high living polymerization property but also an improvement in initiation efficiency are important for anionic polymerization. The improvement in the initiation efficiency is especially important for synthesis of a block copolymer as well as enhancement of use efficiency of a polymerization initiator compound. For example, the following process is assumed: a process for synthesizing a block copolymer comprising a polymer block resulting from a certain kind of monomer (hereinafter referred to as a first monomer) and another polymer block resulting from another kind of monomer (hereinafter referred to as a second monomer), comprising polymerizing the first monomer to synthesize a living polymer, and then polymerizing the second monomer by use of the living monomer as a polymerization initiator compound. If the initiation efficiency of the living polymer (block efficiency in this case) is low, a product which is actually obtained is a mixture of the block copolymer and a polymer resulting from the first monomer. In many cases, the above-mentioned impurity produced by interruption of the polymerization causes a remarkable drop in performances of the block copolymer. It is known that, for example, a triblock copolymer having a structure of a hard block/a soft block/a hard block has properties as a thermoplastic elastomer. If a polymer having only a hard block or a diblock copolymer having a structure of a hard block/a soft block is mixed with this type triblock copolymer, mechanical properties such as tensile strength drop. Block copolymers are frequently used as compatibilizer for different resins. However, if a homopolymer is mixed with a used block copolymer, the function as the compatibilizer deteriorates so that good points which respective resins originally have in a resultant resin composition are not sufficiently exhibited.
As a process for heightening initiation efficiency in anionic polymerization of a methacrylic ester or an acrylic ester, there is known a process comprising the steps of subjecting an organic alkali metal compound, for example, an alkyl lithium such as butyllithium, or a lithiated polymer such as polystyryllithium to addition reaction with 1,1-diphenylethylene or &agr;-methylstyrene to prepare a compound having, at its terminal site, a diphenylmethylene anion structure or a phenylmethylene anion structure; and then polymerizing a methacrylic ester anionically in a solvent comprising tetrahydrofuran alone or a mixture of tetrahydrofuran and toluene at a low temperature, for example, −60° C. or lower, using the above-mentioned compound as a polymerization initiator compound (Macromolecules, Vol. 23, pp. 2618-2622 (1990)). A polar solvent, such as tetrahydrofuran used in this process, is easily mixed in waste water at the time of washing with water after the polymerization, and further is not easily separated from the waste water. Therefore, the polar solvent is not suitable for industrial use. As a result, in order to carry out industrially anionic polymerization in a solution of a methacrylic ester or an acrylic ester, it is desired to use a nonpolar solvent, such as a hydrocarbon based solvent, as a solvent.
As a process for making it possible to polymerize a methacrylic ester or an acrylic ester anionically in a hydrocarbon based solvent, a process wherein an organoaluminum compound causes to be present in the polymerization system is suggested. It is considered that in this case, the organoaluminum compound has a function of lowering nucleophilicity of the growing terminal of the polymer and stabilizing the growing terminal by coordination, as a Lewis acid, to a used polymerization initiator compound or the growing terminal of the living polymer in the middle of the polymerization. Examples of reports on such a polymerization process are as follows.
(1) Anionic polymerization of a methacrylic ester using tert-butyllithium was conducted in the presence of an organoaluminum compound such as a trialkylaluminum or a dialkyl(diphenylamino)aluminum in toluene at −78° C. to obtain a methacrylic ester polymer having a narrow molecular weight distribution (JP-B-H7-57766).
(2) Anionic polymerization of a methacrylic ester using an organolithium compound such as tert-butyllithium was conducted in the presence of a specific organoaluminum compound having one or more bulky groups (for example, triisobutylaluminum or diisobutyl(2,6-di-tert-butyl-4-methylphenoxy)aluminum) in a hydrocarbon solvent at a temperature of about −10° C., which is a relatively mild cooling condition(U.S. Pat. No. 5,180,799).
(3) Anionic polymerization of a methacrylic ester or an acrylic ester using tert-butyllithium was conducted in the presence of methylbis(2,6-di-tert-butylphenoxy)aluminum or ethylbis(2,6-di-tert-butylphenoxy)aluminum in toluene at a temperature of −60° C. or −70° C. to obtain a homopolymer or a block copolymer having a narrow molecular weight distribution (Polymer Preprints. Japan, Vol. 46, No. 7, pp. 1081-1082 (1997) and Vol. 47, No. 2, p.179 (1998)).
(4) An organolithium compound such as tert-butyllithium, sec-butyllithium, ethyl &agr;-lithioisobutyrate, 1,1-diphenylhexyllithium was mixed with an organoaluminum compound such as methylbis(2,6-di-tert-butylphenoxy)aluminum, ethylbis(2,6-di-tert-butylphenoxy)aluminum or tris(2,6-di-tert-butylphenoxy)aluminum, and then the mixture was brought into contact with methyl methacrylate to anionically polymerize methyl methacrylate in a nonpolar organic solvent such as toluene at about room temperature. In this way, an initiation efficiency of 0.05-0.63 was attained (U.S. Pat. No. 5,656,704).
(5) Anionic polymerization of a methacrylic ester or an acrylic ester using an organolithium compound such as methyl &agr;-lithioisobutyrate or tert-butyllithium was conducted in the presence of an organoaluminum compound, such as a trialkylaluminum, and an ester compound, an ether compound or an organic quaternary salt in a hydrocarbon based solvent such as toluene at a temperature of about −80° C. to 0° C., so as to obtain a polymer having a narrow molecular weight distribution (Macromolecules, Vol. 31, pp. 573-577 (1998) and International Publication WO98/23651).
(6) An organolithium compound such as n-butyllithium was subjected to addition-reaction with butadiene to prepare polybutadienyllithium, and then the polybutadienyllithium was reacted with tert-butyl methacrylate in the presence of a trialkylaluminum such as triethylaluminum at 50° C., so as to obtain a block copolymer (U.S. Pat. No. 5,514,753).
According to the above-mentioned processes (1)-(6), anionic polymerization of a methacrylic ester or an acrylic ester can be attained in a hydrocarbon based solvent. However, in order to use these processes as industrial polymerization processes, they have the following points to be further improved.
The polymerization initiator compound used to polymerize a methacrylic ester or an acrylic ester in specific polymerization examples in the above-mentioned (1)-(3) processes is limited to tert-butyllithium. It can be presumed that in order to attain good polymerization results in these polymerization examples, it is preferred to use tert-butyllithium. However, tert-butyllithium has intense self-ignition ability. Thus, if tert-butyllithium is industrially used, problems about safety and handling performances thereof upon transportation and storage thereof arise.
In the processes (1) and (3), the polymerization temperatures used in specific
Akai Makoto
Hamada Kenichi
Ishiura Kazushige
Ono Tomohiro
Shachi Kenji
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Zalukaeva Tatyana
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