Akinori Toyota

Propylene homo- and copolymerization with ethylene using an ethylenebis(1-indenyl) zirconium dichloride and methylaluminoxane catalyst system

Abstract Isotactic polypropylene obtained with a rac-ethylenebis(1-indenyl)zirconium dichloride and methyl-aluminoxane catalyst system in the range −30 to 50°C was successively fractionated by boiling pentane, hexane, heptane and trichloroethylene, with the result that the hexane-insoluble/heptane-soluble portion was the major fraction for all samples. The whole and fractionated polymers were characterized in comparison with those of an MgCl 2 TiCl 4  Et 3 Al catalyst system by 13C nuclear magnetic resonance, gel permeation chromatography and differential scanning calorimetry. In copolymers with ethylene, three types of regio-irregular structures depending on ethylene content were observed by 13C nuclear magnetic resonance.

Studies on propylene polymerization with a highly active MgCl2 supported TiCl4 catalyst system

SummaryPropylene polymerization was performed with a highly active MgCl supported TiCl4 in conjunction with Et3Al and ethyl benzoate (EB). The obtained polypropylene sample was separated into four fractions by successive extraction with pentane, heptane and trichloroethylene (trichlene). Yield, Mn, Tm and microtacticity of each fraction were determined, and the effects of the concentration of EB on these items of results were investigated. It has been found that EB enhances yield, Mn and stereospecificity of trichlene insoluble (the most stereospecific) fraction, and in contrast, it decreases rapidly yields of other three fractions without changing the character of the polymers. From these findings, the functions of EB to the active centers were discussed.

Polymerization of propylene with an ethylene bis(1-indenyl) hafnium dichloride and methylaluminoxane catalyst system

Abstract Propylene polymerizations have been performed using ethylene bis(1-in-denyl) hafnium dichloride containing a small quantity of a zirconium compound and methylaluminoxane as the catalyst system over the temperature range −30°C to 50 °C. As a result, isotactic polypropylene (PP) has been obtained whose meso-meso (mm ) triad sequence content is greater than 92% as demonstrated by 13 C NMR spectroscopy, and whose molecular weight is comparable to that for commercially produced PP. The GPC curves for PP exhibit a remarkable change in shape depending on the polymerization temperature leading to ones which clearly exhibit separate bimodal shapes. The microstructure and melting point of PP have also been investigated.

MgCl2 supported titanium catalyst prepared by mechanical pulverization

SummaryMgCl2 supported titanium catalysts were prepared by mechanical pulverization or MgCl2 with titanium compounds using two types of machines, rotatory mill and vibratory mill. Both methods gave substantially the same results, although vibratory mill much saved the milling time. The nature of the fixed titanium compounds was not homogeneous, and the titanium compounds fixed at an earlier stage of milling, which could be located at exposed “active” edge positions of MgCl2 particles, showed higher activity in ethylene polymerization. On the other hand, those fixed at the later stage showed lower activity and caused reaggregation of the particles. Furthermore, chlorine-free titanate compounds, Ti(OBu)4 and Ti(OEt)4, also could be fixed on MgCl2 which showed high activity in ethylene polymerization.

Synthesis and characterization of metallocene-catalyzed propylene-ethylene copolymer with end-capped functionality

Abstract Metallocene-catalyzed propylene–ethylene copolymer (PER) having a terminal vinylidene group, reacted with maleic anhydride without free radical conditions to prepare terminally MAH-functionalized PER. Through the analysis of the obtained polymer by 13 C NMR spectroscopy, it was shown that a large part of a terminal vinylidene group isomerizes to a more stable internal double bond in this reaction and that the PER–MAH is formed via the reaction of MAH with isomerized PER and original PER.

Solution copolymerization of ethylene with α-olefin by vanadium catalyst

SummaryCopolymerization of ethylene with an α-olefin, i.e. propylene, butene-1 and 4-methyl-pentene-1(4-MP-1), was carried out by vanadium catalyst prepared by treating VOCl3 with (n-C8H17)3Al in decane in combination with Et3Al and CHCl3. The copolymerization system was homogeneous at a temperature as high as 170 °C. It has been revealed that the monomer insertion reaction of irregular direction, i.e. the insertion giving rise to the growing end of secondary alkyl / catalyst bond, occurs occasionally at the propagation of the α-olefin comonomer. The irregular insertion takes place most frequently with 4-MP-1. The chain transfer with hydrogen takes place more preferentially at the irregular propagation end in comparison with the regular one.

SYNTHESIS OF NOVEL BI-FUNCTIONAL COPOLYMER BEARING STERICALLY HINDERED PHENOL AND HINDERED AMINE GROUPS VIA RING-OPENING METATHESIS POLYMERIZATION

Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene (M1) and 3,3,5,5- etramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate (M2) were synthesized and polymerized by RuCl2 (=CHPh)(PCy3)2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol (SHP) and hindered amine (HLAS) groups via ring-opening metathesis polymerization (ROMP). The resulting copolymers were characterized by gel permeation chromatography (GPC), 1H-NMR and differential scanning calorimetry (DSC). The number average molecular weight (Mn) and functional unit content of the resulting copolymer could be regulated by varying the concentration of catalyst and monomer feed.

Solution copolymerization of ethylene with α-olefins by a MgCl2 supported TiCl4 catalyst

SummaryCopolymerization of ethylene with α-olefins, i.e. propylene, butene-1, 4-methyl-pentene-1(4-MP-1), was carried out by a MgCl2 supported TiCl4 catalyst in combination with Et3Al at a temperature as high as 170 °C at which the polymerization system was homogeneous. This catalytic system showed very a high activity and produced copolymers having a density of 0.91–0.94 g/ml. Of these three kinds of comonomers, propylene showed the highest reactivity and caused most frequently the termination of a polymer growing by chain transfer reaction and produced copolymers having the broadest MWD.

Synthesis, Characterization and Radical Scavenging Ability of 3,5-di-tert-Butyl-4-hydroxyphenoxy-Functionalized Polynorbornenes Synthesized Using Ring-Opening Metathesis Polymerization

Novel norbornene derivatives bearing a 3,5-di-tert-butyl-4-hydroxyphenoxy (DBHO) group were synthesized and used as sterically hindered phenol functionalized norbornene monomers (1–4). The ring-opening metathesis polymerization (ROMP) of these functional monomers was carried out with a typical ruthenium catalyst (bis(tricyclohexylphosphine)benzylidene ruthenium (IV) dichloride, a Grubbs first-generation catalyst) to prepare sterically-hindered phenol-functionalized polymers possessing radical scavenging function. The resulting polymers bearing a DBHO side-chain were characterized by means of gel-permeation chromatography, 1H-NMR and 13C-NMR. The radical scavenging ability of polymers was determined using the α,α-diphenyl-β-picrylhydrazyl (DPPH⋅) free radical. Due to the electron-donating effect of the oxygen atom located in the para-position of phenol, the resulting polymers showed high efficiency to scavenge DPPH⋅free radical. The molecular weight of polymers was dependent on the molar ratio of monomer to catalyst ([M]/[C]), and the ROMP activity was dependent on the stereostructure of monomers themselves.

Copolymerization of styrene derivatives and cycloolefin with Ni compound/MAO catalyst

Copolymerization of styrene derivatives, such as 4-tert-butylstyrene (4TBS), 4-methylstyrene (4MS), 4-methoxystyrene (4MOS), 4-bromostyrene (4BS), and 5-ethylidene-2-norbomene (ENB) was conducted with nickel (Ni) compound/methylaluminoxane (MAO) catalysts. Polymerization behaviors and properties of the resulting copolymers were investigated. Nickel bis(acetylacetonate) (1) / MAO showed the highest activity. Tg values of the obtained copolymers reached to ca. 300 °C.