| 摘要 |
The present invention relates to an improved gas-phase process for producing in-situ TPO's or copolymers of propylene and ethylene in multiple reactors using high activity Ti/Al catalysts is provided. The improvement consists of developing a control parameter derived from eight integral regions of the copolymer <1><3>C NMR spectrum, defining the limits of the control parameter for the process, and operating the process to maintain the parameter within the defined limits. This is accomplished by adjusting the amount of ethylene fed to the reactors and adjusting other process variables as required. The present invention is further directed to tough, puncture- and tear-resistant films having a high degree of flexibility and softness are provided. The monolayer and multilayer films of the invention are obtained using copolymers of propylene with 8 to 40 weight percent ethylene produced by gas phase polymerization of the monomers in dual reactors. The films will have a 1% secant modulus from 5,000 psi to 70,000 psi. Melting points of these films are higher than that of low density polyethylene and, most generally, in the range 125 DEG C to 160 DEG C. <IMAGE> |
