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Norio Tomotsu

Bio: Norio Tomotsu is an academic researcher. The author has contributed to research in topics: Polymerization & Styrene. The author has an hindex of 5, co-authored 12 publications receiving 245 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, some mechanistic models for polymerization and stereo-regulation as well as the factors which affect the activity and stereospecificity of the catalysts are discussed, and the effects of substitutions on Cp ligand of half titanocene complexes were examined.
Abstract: Syndiotactic polystyrene, namely XAREC® is being developed by Idemitsu Petrochemical Co., Ltd. as a major new polymer family. XAREC® is a new crystalline engineering thermoplastic with a crystalline melting point of 270 °C. Because of its crystalline nature, XAREC® has a high heat resistance, an excellent chemical resistance and a water/steam resistance. XAREC® also has the dip soldering resistance. Potential applications for XAREC® include surface-mount electronic devices and electrical connectors. In this paper, some mechanistic models for polymerization and stereo-regulation as well as the factors which affect the activity and stereospecificity of the catalysts are discussed. The effects of substitutions on Cp ligand of half titanocene complexes were examined. The bulky substitution groups reduce the activity. Also, borate compounds as activator and effects of hydrogen are discussed.

171 citations

Journal ArticleDOI
TL;DR: In this article, the current development of the metallocene-based catalysts for syndiotactic polystyrene (SPS) has been reviewed and some mechanistic models for polymerization and stereoregulation, as well as the factors which affect the activity and stereospecificity of the catalysts are discussed.
Abstract: The current development of the metallocene-based catalysts for syndiotactic polystyrene (SPS) has been reviewed. SPS is a new semi-crystalline engineering thermoplastic with a crystalline melting point of 270°C. Because of its crystalline nature, SPS has high heat resistance, excellent chemical resistance and waterysteam resistance. In this review, some mechanistic models for polymerization and stereoregulation, as well as the factors which affect the activity and stereospecificity of the catalysts, are discussed.

27 citations

Journal ArticleDOI
TL;DR: In this paper, various malonate compounds with different substituents (R 1 R 2 C(COOBu) 2 ) were systematically synthesized and investigated for use as an internal donor (ID) in combination with a MgCl 2 -supported TiCl 4 type catalyst, a triethylaluminum (TEA) co-catalyst and an alkoxysilane external donor (ED) for application in propylene polymerization.
Abstract: Various new malonate compounds (R 1 R 2 C(COOBu) 2 ) with different substituents (R 1 , R 2 ) were systematically synthesized and investigated for use as an internal donor (ID) in combination with a MgCl 2 -supported TiCl 4 type catalyst, a triethylaluminum (TEA) co-catalyst and an alkoxysilane external donor (ED) for application in propylene polymerization. The catalytic activity and isotacticity of polypropylene (PP) greatly depended on not only the oxygen electron density of the ED, but also on the molecular volume of the ID. Furthermore, the mechanism of the active site formation was discussed with respect to the composition of the catalyst treated with TEA and ED, and with respect to the temperature rising elution fractionation (TREF) results of PP and so on. It was presumed that the desorption of malonates near Ti species from MgCl 2 caused the generation of atactic PP sites, and the decrease of the isotacticity of PP.

27 citations

Book ChapterDOI
TL;DR: In this article, a good relationship between electron density of titanium and the space for styrene coordination was found, where the bulky substituent groups reduce the catalyst activity and electron donative substitution groups increase the catalytic activity.
Abstract: Catalysts for syndiospecific polymerization of styrene are examined. Among the transition metal complexes, complexes with titanium and one cyclopentadienyl(Cp) ligand show high catalyst activity. Titanium complexes with different substituent groups on Cp ligand were examined and a good relationship between electron density of titanium and the space for styrene coordination was found. The bulky substituent groups reduce the catalyst activity and electron donative substitution groups increase the catalyst activity. Small amount of hydrogen increases the catalyst activity. However, excess amount of hydrogen makes molecular weight distribution broaden. There seems to be two kinds of active site for the styrene polymerization under the conditions. Titanium complexes with various types of tetraphenylborates were examined. The number of fluorine on the phenyl group of borate improves the catalyst activity and by-products from the reaction of triisobutylaluminum, borate and titanium complex may coordinate the active site and decrease the catalyst activity.

9 citations


Cited by
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Journal ArticleDOI
TL;DR: Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.
Abstract: One of the most exciting developments in the areas of catalysis, organometallic chemistry, and polymer science in recent years has been the intense exploration and commercialization of new polymerization technologies based on single-site and metallocene coordination olefin polymerization catalysts.1 The vast number of specifically designed/synthesized transition metal complexes (catalyst precursors) and main-group organometallic compounds (cocatalysts) allows unprecedented control over polymer microstructure, the generation of new polymer architectures, and the development of new polymerization reactions. Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.2-4 The intense industrial activity in the field and the challenges to our basic understanding that have come to light have in turn 1391 Chem. Rev. 2000, 100, 1391−1434

1,719 citations

Journal ArticleDOI
TL;DR: This Review gives a comprehensive overview of post-metallocene polymerization catalysts that have been put into practice and the decisive properties for this success of a given catalyst structure are delineated.
Abstract: Research on "post-metallocene" polymerization catalysis ranges methodologically from fundamental mechanistic studies of polymerization reactions over catalyst design to material properties of the polyolefins prepared. A common goal of these studies is the creation of practically useful new polyolefin materials or polymerization processes. This Review gives a comprehensive overview of post-metallocene polymerization catalysts that have been put into practice. The decisive properties for this success of a given catalyst structure are delineated.

362 citations

Journal ArticleDOI
TL;DR: This catalyst system could also effect the syndiospecific copolymerization of styrene with ethylene to yield Styrene-ethylene copolymers having syndiotactic styrene-styrene sequences, which are expected to show novel properties.
Abstract: On treatment with 1 equiv of [Ph3C][B(C6F5)4], the scandium half-sandwich bis(alkyl) complex (C5Me4SiMe3)Sc(CH2SiMe3)2(THF) showed extremely high activity (up to 1.36 × 104 kg of sPS/(mol Sc·h)) and syndiospecificity (rrrr > 99%) for the polymerization of styrene at room temperature in toluene. More remarkably, this catalyst system could also effect the syndiospecific copolymerization of styrene with ethylene to yield styrene−ethylene copolymers having syndiotactic styrene−styrene sequences. The styrene content in the copolymers could be easily controlled by changing the styrene feed and could reach higher than 80 mol %. This is the first example of formation of such types of styrene−ethylene copolymers, which are expected to show novel properties.

298 citations