An ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms has a density f from 0.940 to 0.960 g/cm.sup.3, a molecular weight distribution, Mw/Mn of from 9 to 12, and a Z-average molecular weight, Mz of greater than 500,000. The ethylene copolymer is made in a multi-zone reactor system under solution phase polymerization conditions and is useful in the preparation of biaxially oriented polyethylene (BOPE) films.

An ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms has a density f from 0.940 to 0.960 g/cm.sup.3, a molecular weight distribution, Mw/Mn of from 9 to 12, and a Z-average molecular weight, Mz of greater than 500,000. The ethylene copolymer is made in a multi-zone reactor system under solution phase polymerization conditions and is useful in the preparation of biaxially oriented polyethylene (BOPE) films.

An ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms has a density f from 0.940 to 0.960 g/cm.sup.3, a molecular weight distribution, Mw/Mn of from 9 to 12, and a Z-average molecular weight, Mz of greater than 500,000. The ethylene copolymer is made in a multi-zone reactor system under solution phase polymerization conditions and is useful in the preparation of biaxially oriented polyethylene (BOPE) films.

Methods for producing a polymer include contacting at least one monomer under polymerization conditions with a fluidized bed of a polymerization catalyst on a particulate support; measuring a plurality of pressures of the fluidized bed at a plurality of locations corresponding to increasing heights from a bottom of the fluidized bed; calculating a plurality of pressure drops between the plurality of locations based on the measured pressures; performing a regression analysis on the calculated plurality of pressure drops; correlating the plurality of pressure drops to corresponding heights from the bottom of the fluidized bed based on the regression analysis; determining a height of the fluidized bed based on the correlating; and controlling polymerization conditions based on the determined height of the fluidized bed. The method can also be used to detect malfunctioning pressure transducers based on deviation between measured and expected values.

Methods for producing a polymer include contacting at least one monomer under polymerization conditions with a fluidized bed of a polymerization catalyst on a particulate support; measuring a plurality of pressures of the fluidized bed at a plurality of locations corresponding to increasing heights from a bottom of the fluidized bed; calculating a plurality of pressure drops between the plurality of locations based on the measured pressures; performing a regression analysis on the calculated plurality of pressure drops; correlating the plurality of pressure drops to corresponding heights from the bottom of the fluidized bed based on the regression analysis; determining a height of the fluidized bed based on the correlating; and controlling polymerization conditions based on the determined height of the fluidized bed. The method can also be used to detect malfunctioning pressure transducers based on deviation between measured and expected values.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that the amount of smoke generated during processing of a polyethylene to be obtained is small, and the number of fish eyes contained in a film formed from the polyethylene is small. An apparatus for manufacturing high pressure method polyethylene includes: an ethylene supply line that is a line branched from a high pressure recycle ethylene line and connected to a recycle ethylene holding drum for decompressing high pressure recycle ethylene from the high pressure recycle ethylene line and supplying the decompressed recycle ethylene to the recycle ethylene holding drum; and the recycle ethylene holding drum that is a drum for holding the decompressed recycle ethylene through the ethylene supply line.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that the amount of smoke generated during processing of a polyethylene to be obtained is small, and the number of fish eyes contained in a film formed from the polyethylene is small. An apparatus for manufacturing high pressure method polyethylene includes: an ethylene supply line that is a line branched from a high pressure recycle ethylene line and connected to a recycle ethylene holding drum for decompressing high pressure recycle ethylene from the high pressure recycle ethylene line and supplying the decompressed recycle ethylene to the recycle ethylene holding drum; and the recycle ethylene holding drum that is a drum for holding the decompressed recycle ethylene through the ethylene supply line.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that a chain transfer agent can be supplied by a simpler apparatus, a deviation (variation) of the concentration of the chain transfer agent supplied to a reactor can be reduced, and compression energy of the chain transfer agent can be reduced. An apparatus for manufacturing high-pressure method polyethylene includes a chain transfer agent supply line that is a line connected to a low pressure recycle ethylene supply line for supplying a chain transfer agent.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that a chain transfer agent can be supplied by a simpler apparatus, a deviation (variation) of the concentration of the chain transfer agent supplied to a reactor can be reduced, and compression energy of the chain transfer agent can be reduced. An apparatus for manufacturing high-pressure method polyethylene includes a chain transfer agent supply line that is a line connected to a low pressure recycle ethylene supply line for supplying a chain transfer agent.

The present invention relates to a method for improving the cooling capacity of a gas solids olefin polymerization reactor by splitting the fluidization gas and returning part of the fluidization gas to the reactor into the bottom zone of the reactor and another part of the fluidization gas directly into the dense phase formed by particles of a polymer of the at least one olefin suspended in an upwards flowing stream of the fluidization gas in the middle zone of the reactor.