Abstract: A polyethylene resin comprising from 44 to 55 wt % of a high molecular weight polyethylene fraction, and from 45 to 56 wt % of a low molecular weight polyethylene fraction; the high molecular weight polyethylene fraction comprising a linear low density polyethylene having a density of from 0.913 to 0.923 g/cm3, and an HLMI of from 0.02 to 0.2 g/10 min; and the low molecular weight polyethylene fraction comprising a high density polyethylene having a density of at least 0.969 g/cm3 and an MI2 of greater than 100 g/10 min; wherein the relationship between the density D of the resin in g/cm3 and the weight fraction of the low molecular weight fraction P1 is defined by 0.055P1+0.916<D<0.034P1+0.937.

Abstract: A process comprising polymerising in a loop reactor an olefin monomer optionally together with an olefin commoner in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Fronde number is maintained at or below 20 is disclosed.

Abstract: A process comprising polymerizing an olefin monomer optionally together with an olefin comonomer in the presence of a polymerization catalyst in a diluent in a loop reactor which comprises at least 2 horizontal sections and at least 2 vertical sections to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number in at least 20% of the length of the vertical sections of the reactor loop is less than 85% of the Froude number in at least 20% of the length of the horizontal sections of the loop is disclosed.

Abstract: A polyethylene resin suitable for formation into pipes or pipe fittings is disclosed, having an MI5 of from 0.40 to 0.70 g/10 min, and comprising from 47 to 52 wt % of a low molecular weight polyethylene fraction, and from 48 to 53 wt % of a high molecular weight polyethylene fraction, wherein the high molecular weight polyethylene fraction comprises a copolymer of ethylene and 1-hexen or 1-octene.

Abstract: Drawn tape, fiber or filament including a multimodal resin having a density of at least 940 kg/m3, a melt index MI5 of 0.05 to 5 g/10 min, and a molecular weight distribution of the resin being less than 40.

Abstract: A process for the separation of volatile material from particulate polymer discharged from a polymerisation reactor in the form of a polymer slurry and which has been substantially freed from unreacted monomer in an earlier separation step, comprising (a) feeding the particulate polymer to a purge vessel and causing it to move through the vessel in substantially plug-flow mode, (b) heating the particulate polymer in the purge vessel to a temperature greater than 30° C.

Abstract: A process comprising polymerising in a loop reactor an olefin monomer optionally together with an olefin commoner in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number is maintained at or below 20 is disclosed.

Abstract: A process comprising polymerising in a loop reactor of continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the internal diameter of at least 50% of the total length of the reactor is at least 700 millimeters and the solids concentration in the reactor is at least 20 volume % is disclosed.

Abstract: A process for the separation of volatile material from particulate polymer which has been substantially freed from unreacted monomer in an earlier separation step, comprising (a) feeding the particulate polymer to a purge vessel, optionally causing it to move through the vessel in substantially plug-flow mode, (b) heating the particulate polymer in the purge vessel to a temperature grater than 30° C. but insufficiently high to cause the particles to become agglomerated, and/or maintaining the polymer at a temperature in this range in the purge vessel, (c) feeding gas to the purge vessel counter-current to the movement of the particulate polymer to remove volatile material therefrom, (d) removing the particulate polymer from the purge vessel, wherein substantially all of the heating of the particles which occurs in the purge vessel is accomplished by preheating the gas fed into the purge vessel.

Abstract: A process for the polymerisation of olefins is disclosed wherein at least part of a stream, preferably a catalytically active stream, withdrawn from a polymerisation reactor is passed through a fractionator so as to remove hydrogen and active fines.

Abstract: A polymerisation process is disclosed in which polyethylene is produced in slurry in a polymerisation reactor in the presence of a Ziegler Natta catalyst and an activator, and slurry containing the polymer is withdrawn from the reactor and transferred to a flash tank operating at a pressure and temperature such that at least 50 mol % of the liquid component of the slurry is withdrawn from the flash tank as a vapour and at least 98 mol %, more preferably at least 98.5 mol %, and most preferably at least 99.5 mol %, of the vapour withdrawn from the flash tank is capable of being condensed at a temperature of between 15 and 40C without compression, wherein a by-product suppressor, which reduces the amount of by-product formed per unit of polyethylene produced by at least 10% compared with an identical polymerisation process where the by-product suppressor is not present, is used in the reactor.

Abstract: A process for the polymerisation of olefins is disclosed wherein at least part of a stream, preferably a catalytically active stream, withdrawn from a polymerisation reactor is passed through a fractionator so as to remove hydrogen and active fines.

Abstract: A process comprising polymerising in a loop reactor of a continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the average internal diameter of at least 50% of the total length of the reactor is at least 650 millimeters, the solids concentration in the reactor is at least 15 volume % and having a particle size distribution such that (D90?D10)/D50 is less than 2.

Abstract: Process comprising polymerising in a loop reactor of a continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent, wherein the average internal diameter of at least 50% of the total length of the continuous tubular loop reactor is at least 700 mm wherein the HMW polymer is produced in a reactor upstream of the LMW polymer reactor and the ratio of the average internal diameter of the HMW reactor to the average internal diameter of the LMW reactor is between 0.8 and 1.4.

Abstract: A process for controlling a slurry phase (co-) polymerisation process in the presence of a polymerisation catalyst, which comprises maintaining the density SPAN of the polymer powder particles (defined as the absolute value of the density difference in g/cm3 between the average density of the polymer particles exiting the reactor with particle size above D90 and the average density of the material with particle size below D10) below 0.005, preferably below 0.003, more preferably below 0.0026, most preferably below 0.0023.

Abstract: A process is disclosed for providing a flow of particulate matter such as a catalyst to a reactor, comprising intermittently adding said particulate matter and a diluent to a mixing tank, and continuously withdrawing a slurry of particulate matter in diluent from the mixing tank for introduction into the reactor, wherein prior to each addition of particulate matter and diluent to the mixing tank, the concentration of particulate matter in the diluent already in the mixing tank is measured or calculated, and the amount of particulate matter and diluent subsequently added is measured so as to achieve the same concentration at the end of the addition as that measured or calculated prior to the addition. Preferably measurement of the amount of particulate matter and diluent added to the mixing tank is carried out before any diluent is added to the particulate matter.

Abstract: Process for polymerising an olefin monomer in at least one continuous tubular loop reactor of a multiple reactor system, optionally together with an olefin comonomer, in the presence of a polymerisation catalyst in a diluent, to produce a slurry containing solid particulate olefin polymer and diluent. The average internal diameter of at least 50% of the total length of the continuous tubular loop reactor is at least 700 mm. A high molecular weight (HMW) polymer is made in a first reactor and a low molecular weight (LMW) polymer is made in a second reactor, the first (HMW) reactor having a space time yield (defined as production of polymer in kg/h per unit volume of reactor) greater than 100 kg/m3/h, and the ratio of space time yield in the first (HMW) reactor to the second (LMW) reactor is greater than 1.

Abstract: An olefin polymerisation process is disclosed in which a slurry of olefin polymer is produced within a polymerisation zone, and a polymer slurry stream is withdrawn from the polymerisation zone and passed through a transfer line to a centrifugal concentrating device, which separates it into a solids-lean stream or streams each having a solids concentration less than that of the polymer slurry stream entering the concentrating device and a solids-rich stream or streams each having a solids concentration greater than that of the polymer slurry stream entering the concentrating device, wherein at least part of the solids-rich stream or streams is recycled back into the polymer slurry stream upstream of the concentrating device and downstream of the polymerisation zone.

Abstract: A process is disclosed for providing a flow of particulate matter such as a catalyst to a reactor, comprising intermittently adding said particulate matter and a diluent to a mixing tank, and continuously withdrawing a slurry of particulate matter in diluent from the mixing tank for introduction into the reactor, wherein prior to each addition of particulate matter and diluent to the mixing tank, the concentration of particulate matter in the diluent already in the mixing tank is measured or calculated, and the amount of particulate matter and diluent subsequently added is measured so as to achieve the same concentration at the end of the addition as that measured or calculated prior to the addition. Preferably measurement of the amount of particulate mailer and diluent added to the mixing tank is carried out before any diluent is added to the particulate matter.

Abstract: Polyethylene resin suitable for formation into pipes or pipe fittings having an M15 of from 0.40 to 0.70 g/10 min, and including from 47 to 52 wt % of a low molecular weight polyethylene fraction, and from 48 to 53 wt % of a high molecular weight polyethylene fraction. The high molecular weight polyethylene fraction includes a copolymer of ethylene and 1-hexen or 1-octene, and the resin has a density after granulation and addition of additives of between 957 kg/m3 and 963 kg/m3.