摘要:
An olefin polymerization process in which at least two introductions of hydrogen are made during the olefin polymerization reaction. Suitable catalysts include metallocenes of the general formula (Cp) m TiX n , wherein Cp is a substituted or unsubstituted cyclopentadienyl ring, X is a halogen, m=1-2, n=2-3, and wherein m+n=4 , and conventional Ziegler-Natta catalysts blended with or modified by such metallocenes.
摘要:
This invention describes a process for preparing isotactic poly-alpha olefin of melt flow equal to or less than 8 dg/min comprising the steps of:
A. providing a suitable catalyst system capable of producing isotactic poly-alpha olefin comprising a metallocene-type catalyst, an alumoxane as cocatalyst or catalyst activator, and optionally a catalyst support; B. ripening the suitable catalyst system of step A by contacting with an alkyl aluminum for a period of time of from 6 hours to 14 days ; C. polymerising a suitable monomer using the ripened catalyst system of step B ; and recovering the desired isotactic polyolefin.
摘要:
Method of improving the crystallization rate and temperature of syndiotactic polypropylene by addition of at least one of polytetrafluoroethylene, sodium 2,2-methylene-bis-(4,6,di-tert-butylphenyl)phosphate)), pimellic acid, and calcium pimallate, and compositions and products made thereby.
摘要:
A new synthesis of a Ziegler-Natta catalyst uses a multi-step preparation which includes treating a soluble magnesium compound with successively stronger chlorination/titanation reagents. The catalyst may be used in polymerization of olefins, particularly ethylene, to produce a polymer with less fines, larger average fluff particle size and narrow molecular weight distribution. The catalyst has high activity and good hydrogen response.
摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with an aluminum alkyl and aging the catalyst prior to polymerization. In addition, the catalyst is prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone.
摘要:
The present invention is a process for producing a catalyst system to produce polymer blends in a single reactor, polymer blends of isotactic polyolefins and syndiotactic polyolefins. The catalyst system is a combination of at least one metallocene catalyst and at least one conventional supported Ziegler-Natta catalyst. The multi-catalyst system is obtained by mixing the components of at least one metallocene catalyst and at least one conventional supported Ziegler-Natta catalyst. The metallocene catalyst comprises a metallocene compound and an ionizing agent. The conventional supported Ziegler-Natta catalyst comprises an aluminum alkyl and a transition metal compound with, optionally, an electron donor.