Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-03-23
2001-12-11
Wu, David W. (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, C526S187000, C526S328000, C526S329700
Reexamination Certificate
active
06329480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a preparation process for acrylic acid ester polymers. More specifically, the present invention pertains to a preparation process of acrylic acid ester polymers including acrylic acid ester homopolymers and block copolymers having at least one polymer block comprising an acrylic acid ester.
2. Description of the Background
On the anionic polymerization of an acrylic acid ester, the following reports (1) and (2) have been made.
(1) An acrylic acid ester homopolymer is available by the solution polymerization of an acrylic acid ester under low-temperature conditions of −78° C. or so in a mixed solvent of toluene and tetrahydrofuran by using an organolithium compound as a polymerization initiator and lithium 2-(2-methoxyethoxy)ethoxide as an additive. A block copolymer having an acrylic acid ester polymer block and a methyl methacrylate polymer block is available by successively carrying out polymerization of an acrylic acid ester and polymerization of methyl methacrylate under the polymerization conditions similar to the above. (See Macromolecules, 27, 4890-4895(1994); Macromolecules, 27, 4908-4913(1994); Journal of Polymer Science: Part A: Polymer Chemistry, 35, 361-369(1997), et al.)
(2) An acrylic acid ester homopolymer is available by the solution polymerization of an acrylic acid ester in toluene under temperature conditions of −60° C. or −78° C. by using t-butyl lithium as a polymerization initiator and methylbis(2,6-di-t-butylphenoxy)aluminum or ethylbis(2,6-di-t-butylphenoxy)aluminum as an additive. A block copolymer having an acrylic acid ester polymer block and a methacrylic acid ester polymer block is available by successively or simultaneously carrying out polymerization of an acrylic acid ester and polymerization of a methacrylic acid ester under the polymerization conditions similar to the above. (See Polymer Preprints, Japan, 46(7), 1081-1082(1997) and ibid, 47(2), 179(1998).)
Anionic polymerization processes which, however, do not relate to an acrylic acid ester but a methacrylic acid ester have been reported as described below in (3) to (6).
(3) Poly(methyl methacrylate) having at least 80% of syndiotacticity is formed by the solution polymerization of methyl methacrylate in toluene by using t-butyl lithium as a polymerization initiator and a trialkyl aluminum as an additive. (See Makromol. Chem., Supplement, 15, 167-185(1989).)
(4) Poly(methyl methacrylate) having syndiotacticity of about 70% is formed by the solution polymerization of methyl methacrylate in toluene in the presence of diisobutyl (2,6-di-t-butyl-4-methylphenoxy)aluminum by using t-butyl lithium as a polymerization initiator. (See Macromolecules, 25, 5907-5913(1992).)
(5) A methacrylic acid ester polymer having a narrow molecular weight distribution is formed by polymerizing a methacrylic acid ester at a temperature range of from −20° C. to +60° C. by using an organic alkali metal compound such as t-butyl lithium as an initiator and a specific organoaluminum compound having at least one bulky group (for example, triisobutylaluminum, diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum, or the like) as an additive. This polymerization process can be applied to the preparation of a block copolymer. (See, U.S. Pat. No. 5,180,799.)
(6) Poly(methyl methacrylate) having an at least 70% content of syndiotactic triads can be obtained by mixing an organolithium initiator with a ligand 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 at a temperature of at least 0° C. and then adding methyl methacrylate to the resulting mixture to anionically polymerize said methyl methacrylate. This process is applicable to the preparation of a block copolymer having a polymer block composed of methyl methacrylate and another polymer block composed of a monomer selected from another methacrylic monomer, aromatic vinyl monomer, diene and maleimide. (See U.S. Pat. No. 5,656,704.)
According to the U.S. Pat. No. 5,180,799 described above in (5), the polymerization reaction is suppressed when the anionic polymerization process of a methacrylic acid ester as described in the patent in the presence of an organoaluminum compound having a bulky group is applied to an acrylic hydrogen atom-containing monomer.
Upon anionic polymerization of a monomer on an industrial scale, it is not completely avoidable that a polymerization initiator to be used has already been partially deactivated and the deactivation of the polymerization initiator proceeds further in the polymerization system owing to the impurities, such as water, which are introduced into the polymerization system as a mixture with the monomer, solvent or the like. Accordingly, it is impossible to prepare a polymer having a desired molecular weight with good reproducibility even by carrying out anionic polymerization using stoichiometric amounts of a polymerization initiator and a monomer calculated based on the desired molecular weight of the polymer. When the living properties in anionic polymerization are high, in other words, when a living polymer with a long-life active anionic end is formed in the reaction system, a polymer having a desired molecular weight and a narrow molecular weight distribution can be prepared with good reproducibility by polymerizing a monomer in an amount smaller than the stoichiometric amount calculated based on the amount of a polymerization initiator used, thereby forming a living polymer; and polymerizing the additional amount of the monomer with the living polymer, after measuring the molecular weight of the living polymer, calculating the number of moles of the living polymer based on the molecular weight of the living polymer and amount of the monomer, and calculating the additional amount of the monomer based on the molecular weight and the number of moles of the living polymer and the desired molecular weight of the final polymer. When the living properties are low in the anionic polymerization, on the other hand, even if a two-stage polymerization technique as described above is employed, a polymer available by the second stage polymerization inevitably has both a component lower in molecular weight and a component higher in molecular weight, than that desired and therefore has a wide molecular weight distribution. This results from the time-dependent marked deactivation of anions at the end of the polymer obtained by the first polymerization. Low living properties in the anionic polymerization are accompanied by deactivation which proceeds even during the polymerization reaction so that at a relatively low polymerization rate, the molecular weight distribution of the resulting polymer inevitably becomes wide even by the first-stage polymerizing operation.
For the preparation of a block copolymer by anionic polymerization, a technique of polymerizing a certain monomer to form its living polymer and then adding another monomer to the polymerization system tends to be adopted. Also in this case, the living properties have a large influence on the block formation efficiency.
Since the anionic polymerization of a monomer such as an acrylic acid ester is an exothermic reaction, so that when such anionic polymerization is carried out under cooling conditions in an industrial scale, it becomes very important to control the temperature rise in the polymerization system due to the exothermic heat. With a view to overcoming this problem, a technique of continuously feeding a monomer to the reaction system at a predetermined rate, thereby controlling the polymerization rate is sometimes adopted. When polymerization is conducted by continuously feeding a monomer, however, living properties in the polymerization reaction tend to have an influence on the uniformity of the molecular weight distribution of the resulting polymer. In other words, not so high living properties inevitably widen the molecular weight dis
Hamada Kenichi
Ishiura Kazushige
Kato Masaji
Ono Tomohiro
Uchiumi Naohiko
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wu David W.
Zalukaeva Tanya
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