Junichi Yoshitake

Kinetic study on propylene polymerization with MgCl2/TiCl4-AlEt3/PhCO2Et System — the role of ethyl benzoate

SummaryA kinetic study on propylene polymerization with the catalyst system of MgCl2-supported TiCl4 catalyst(MgCl2/TiCl4) in conjunction with AlEt3 and PhCO2Et (EB) has been made to elucidate the role of ethyl benzoate (EB) which is known to increase stereospecificity of produced polypropylene. It has been found that a part of added EB was fixed on the supported Ti catalyst and that EB modified the isotactic specific centers to increase the kp (iso) value. Thus the productivity of isotactic polymer and the molecular weight of the isotactic polymer(2·104(¯Mn) to 6·104 at 60°C) were increased.

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 butene-1 with highly active MgCl2- supported TiCl4 catalyst system

Abstract Polymerization of butene-1 was carried out with MgCl 2 TiCl 4 - Et 3 Al ethylbenzoate (EB) or 2,2,6,6-tetramethylpiperidine (TMP) catalyst systems and the poly(butene-1) obtained was fractionated into n-decane (C10)-soluble and -insoluble portions. By 13C nuclear magnetic resonance analysis, the frequency of the mmmm pentad of each fraction was determined to be 30–34% for the C10-soluble and 78% for the C10-insoluble fractions. EB or TMP enhanced the stereospecificity by selective poisoning for the formation of C10-soluble polymer and increased the molecular weight of each fraction by a maximum 2–3 times without changing the polydispersity. EB was found to be superior to TMP as a stereospecificity improver.

Kinetic study on propylene polymerization by a high activity catalyst system: MgCl2/TiCl4/PhCO2Et-AlEt3/PhCO2Et

SummaryKinetic study was performed in short time propylene polymerization with a high activity-high stereospecificity catalyst system composed of MgCl2/TiCl4/PhCO2Et with AlEt3/PhCO2Et. The concentration of the active centers, [C*], the propagation rate constant, kp, and the chain transfer rate, rtr, were determined. The change of these values by the change of polymerization conditions, the concentration of monomer, AlEt3, and the temperature, were studied.

Polymerizations of α-olefins and styrene with MgCl2-supported titanium catalyst system: MgCl2/TiCl4/PhCO2Et with AlEt3PhCO2Et

SummaryKinetic analysis was performed in a short time polymerizations of 1-butene,4-methyl-1-pentene and styrene by using a catalyst system composed of MgCl2/TiCl4/PhCO2Et with AlEt3/PhCO2Et which is known as a highly active and highly stereospecific catalyst system in olefin polymerization. The concentration of the active centers, [C*], the propagation rate constant, kp, and the chain transfer rate, rtr, were determined for each monomer. It was found that the values of [C*] were almost same for every monomer, but the values of kp changes widely in the following order: propylene>1-butene>4-methyl-1-pentene>styrene.

Copolymerization of propylene with a small amount of ethylene using a MgCl2/TiCl4 and a TiCl3 catalyst system

SummaryCopolymerization of propylene with a small amount of ethylene and homopolymerization of propylene were performed using a highly active MgCl2/TiCl4-Et3Al/ethyl benzoate(EB) and a conventional TiCl3-Et2AlCl catalyst systems. The obtained polymers were fractionated into n-decane (C10) soluble and insoluble portions. In all homopolymer fractions with the investigated catalyst systems and copolymer fractions with TiCl3 catalyst system, the inversion of the direction of arrangement of the propylene unit was not observed by 13C-NMR analysis. On the other hand, in C10 soluble fractions of copolymer using MgCl2/TiCl4 catalyst system, regardless of the presence of EB, a significant amount of the inversion unit was detected.

A study of the structure and crystallinity of 4-methyl-1-pentene copolymers with 1,5-hexadiene by 13C nuclear magnetic resonance and X-ray diffraction methods

Abstract The structures of two 4-methyl-1-pentene copolymers with 1,5-hexadiene prepared with a Ziegler catalyst system have been studied by 13C nuclear magnetic resonance spectroscopy. The copolymers have been found to have two repeat units, i.e. 4-methyl-1-pentene (A) and 1-methylene-3-cyclopentyl (B) units. The introduction of the rigid cyclic unit into the 4-methyl-1-pentene sequences brings about significant changes in the structure and properties. The resulting two copolymers, which are composed of A and B units in the ratios 83 17 and 57 43 , form ordered molecular aggregates in the amorphous states as confirmed by X-ray diffraction patterns. This result is in contrast to the well known fact that 4-methyl-1-pentene copolymer with 20 mol% of 1-hexene has a crystallinity of about 50%.

Polymerization of Styrene Versus Propylene with MgCl 2 -Supported Catalysts

It is well known that MgCl2-supported TiC14 (MgC12/TiC14) catalyst in combination with A1Et3 shows much higher activity in propylene polymerization than the conventional TiC13 catalyst system,1 but the stereospecificity of the obtained polymer is rather low, namely 20–40% as isotactic index (I.I.). In a study of kinetics on short time polymerization,2 it was concluded that a cause of the low stereospecificity of this catalyst system was due to the high concentration of atactic active centers ([C*]ata = 14–58%). We also reported that a catalyst system composed of MgC12/TiC14/ethyl benzoate- A1Et3/ethyl benzoate showed very high stereospecificity in both propylene and styrene polymerization and the concentration of the isotactic active centers in both polymerizations was similar,3,4 ([C*]iso(PP)) = 1.3%, [C*]iso(St) = 3%, suggesting comparable isotactic active centers for both monomers.