Novel zirconocene catalysts for the production of high molecular weight LLDPE in high-temperature polymerization

Yano, Akihiro; Sone, Makoto; Hasegawa, Saiki; Sato, M.; Akimoto, Akira

doi:10.1002/(sici)1521-3935(19990401)200:4<933::aid-macp933>3.3.co;2-m

Cited by 6 publications

(10 citation statements)

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“…The continuous reduction of the average rate with increasing temperature above 80 °C in the slurry reactor to 200 °C in the solution reactor indicates that the polymerization kinetics in the slurry were similar to those in solution, even though the active sites were surrounded by growing polymer particles during the slurry polymerization. Decreases in the average rate with increasing temperature in solution reactors were also reported with metallocene catalysts by Charpentier et al14 for ethylene homopolymerization in a continuous reactor and by Yano et al4 for ethylene/1‐butene copolymerization at a high ethylene pressure of 900 bar. Experimental observations in which the average polymerization rate reached the maximum at 155–165 °C for ethylene homopolymerization and ethylene/1‐octene copolymerization in the temperature range of 145–200 °C with a TiCl 4 /MgCl 2 catalyst were reported by Jaber and Ray 15.…”

Section: Resultssupporting

confidence: 58%

“…The ethylene and hydrogen solubilities, estimated with the Peng–Robinson equation and Aspentech HYSIS software, are in good agreement with the results presented by Jaber and Ray. It has been reported that molar masses decrease with increasing polymerization temperature for various modes of reactor operation and catalyst types4, 14–17 because the activation energies for lumped chain terminations are higher than those for chain propagations. The effects of the polymerization temperature on the molar masses of polyethylene made in runs shown in Figures 1 and 2, plus the results at a total pressures of 2.0 MPa, are presented in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…Slurry polymerization is also widely used to test catalysts and to study polymerization behaviors on the laboratory scale 2. The solution process is the first commercial process for manufacturing linear low‐density polyethylene;3 it is mainly used to produce low‐molar‐mass and very low density linear polyethylene with heterogeneous (e.g., Ziegler–Natta catalysts) and homogeneous catalysts (e.g., constrained geometry catalysts and metallocenes) 4…”

Section: Introductionmentioning

confidence: 99%

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Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Wanke

2005

J. Polym. Sci. A Polym. Chem.

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The copolymerization of ethylene and 1-hexene over a spherical polymer/ MgCl 2 -supported TiCl 4 catalyst was studied as a function of the polymerization temperature from 40 to 100 8C in a slurry reactor and from 120 to 200 8C in a solution reactor with triethylaluminum (TEA) as a cocatalyst (1.0-6.8 mmol). The activities increased from 40 to 80 8C and then declined monotonically with increases in the temperature during the slurry and solution polymerizations. The kinetic behavior in the slurry and solution operations was described by the same rate expression. The modeling results indicated that the catalyst had at least two different types of catalytic sites; one site was responsible for the acceleration-decay nature of the activity profiles, whereas the second site resulted in long-term activity. The apparent activation energy for site activation in the slurry operation was 69.9 kJ/mol; no activation energies for site activation could be estimated for the solution operation because the activation process was essentially instantaneous at the higher temperatures. The activation energies for deactivation were 100.3 kJ/mol for the slurry operation and 31.2 kJ/mol for the solution operation. The responses to TEA were similar for the slurry and solution operations; the rates increased with increasing amounts of TEA between 1.0 and 3.4 mmol and then decreased with larger amounts of TEA.

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Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Wanke

2005

J. Polym. Sci. A Polym. Chem.

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“…Molecular weight initially increased with addition of a small amount of the comonomer and then decreased with an increase in 1‐pentene content in the copolymer. This type of behavior is typical for metallocene catalysts, for which it is proposed that α‐olefins at higher concentrations act as chain transfer agents, resulting in low molecular weight copolymers 15, 33–34. It can therefore be assumed that an increase in the 1‐pentene concentration also results in 1‐pentene acting as a chain transfer agent in the 1 /MAO catalyst system.…”

Section: Resultsmentioning

confidence: 86%

Ethylene/1‐pentene copolymers synthesized using the metaloxycarbene complex catalyst system [(CO)₅W=C(Me)OZr(Cp)₂Cl]/MAO

Luruli

Grumel

Brüll

et al. 2004

J. Polym. Sci. A Polym. Chem.

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Ethylene/1-pentene copolymers were prepared using a [(CO) 5 Wϭ C(Me)OZr(Cp) 2 Cl] (1)/MAO catalyst system. 1-Pentene incorporation in the copolymer was monitored using 13 C-NMR spectroscopic methods. The weight average molecular weights (M w ) of the copolymers were between 142,000 and 629,000 g/mol, with polydispersity indexes (PDIs) ranging from Ϸ 2 to 90, as analyzed by size exclusion chromatography (SEC). Melting and crystallization temperatures, determined using differential scanning calorimetry (DSC) and crystallization analysis fractionation (CRYSTAF), decreased linearly as the amount of 1-pentene in the copolymer increased. SEC-FTIR revealed that the 1-pentene is predominantly incorporated in the low molecular weight fraction.

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“…This temperature range is normally employed with metallocene‐based catalysis 19. They also show that at higher temperatures this catalytic system is more active 20. In fact, we carried out polymerization tests at temperatures between 130 and 170 °C, for short periods of time (5 min).…”

Section: Resultsmentioning

confidence: 97%

High‐temperature and high‐pressure ethylene polymerization using a cationic activated metallocene catalytic system

Oliveira

Brandão

Freitas

et al. 2008

Polymer International

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BACKGROUND: Normally, olefin polymerization via metallocene-based catalysis occurs under mild conditions. However, most technology developed for polyolefin production is designed for more severe temperature and pressure processes. Attaining more thermally stable metallocene systems for industrial applications is an important challenge for researchers. RESULTS:A systematic study of ethylene homopolymerization at higher temperatures and pressures, employing the ternary system Ph 2 C(Cp)(Flu)ZrCl 2 /PhNHMe 2 B(C 6 F 5 ) 4 /(i-Bu) 3 Al, is presented The optimal activity for this system is achieved with a Zr/B/Al molar ratio of 1/6/250 and a temperatures of around 130 • C. However, the amount of activator strongly affects the molecular weight and the polydispersity of the polymers produced. Polyethylene produced with Zr/B/Al molar ratios between 1/2/250 and 1/6/250 show no significant difference in their temperature of fusion (T m ) and their crystallinity (X c ). In contrast, in the presence of activator amounts higher than 1/6/250, both the temperature of fusion and polymer crystallinity undergo a steep decrease. All polymers presented lamellar morphology when the activator was present, and an amorphous aspect when the activator was not employed. CONCLUSION:The presence of the activator is essential for thermal stabilization of the catalytic system. Variation of the Zr/B/Al ratio leads to modifications of the catalytic activity as well as to the properties of the polymers synthesized.

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Novel zirconocene catalysts for the production of high molecular weight LLDPE in high-temperature polymerization

Cited by 6 publications

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Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Ethylene/1‐pentene copolymers synthesized using the metaloxycarbene complex catalyst system [(CO)₅W=C(Me)OZr(Cp)₂Cl]/MAO

High‐temperature and high‐pressure ethylene polymerization using a cationic activated metallocene catalytic system

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Novel zirconocene catalysts for the production of high molecular weight LLDPE in high-temperature polymerization

Cited by 6 publications

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Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Kinetic behavior of ethylene/1‐hexene copolymerization in slurry and solution reactors

Ethylene/1‐pentene copolymers synthesized using the metaloxycarbene complex catalyst system [(CO)5W=C(Me)OZr(Cp)2Cl]/MAO

High‐temperature and high‐pressure ethylene polymerization using a cationic activated metallocene catalytic system

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Ethylene/1‐pentene copolymers synthesized using the metaloxycarbene complex catalyst system [(CO)₅W=C(Me)OZr(Cp)₂Cl]/MAO