The Dow Chemical Company

Dow Global Technolgoies LLC

Juan Manuel Mezquita

Otto J Berbee

Ronald Wevers

Karl Zuercher

Werner Zschoch

Gerd Lohse

Harald Beer

The invention pertains to a method for producing ethylene homopolymerizates and ethylene copolymerizates exhibiting a lower mass density of up to 0.930 g/cm and a melt index ranging from 0.15 to 25 g/10 min (2.16 kg; 463 K). Said polymerizates exhibit an improved processing stability and improved availability in the installation at pressures greater than 1000 bar and at temperatures of up to 603 K. The polymerizates are produced in tubular reactors in the presence of radical-forming initiators, oxygen thereunder and chain transfer agents, of which at least one comprises an aldehydic structure. According to the inventive method, chemokinetic characteristics of the reactive feed materials (thermal half-life periods, concentrations, dosing quantities) are coupled with fluidically relevant characteristics of the tubular reactor (flow rate) while taking the target product quality (melt index, flow figure) into consideration. This coupling is carried out such that the interfering secondary reactions, especially polar-inductive substitution effects, which can lead to the formation and the enrichment of organic hydroperoxides are reduced to a minimum and, as a result, extraordinarily stable processing conditions can be obtained.

Method for producing ethylene homopolymerizates and ethylene copolymerizates of a lower mass density

The present invention relates to an ethylene homo or copolymer having a density of between 0.923 and 0.935 g/cm , having a molecular weight distribution M /M of between 3 and 10, and comprising from 0.10 to 0.50 wt. percent of units derived from a carbonyl group containing compound, based on the total weight of the homo or copolymer. In addition, the invention relates to a free radical initiation polymerization process for the preparation of medium density ethylene polymers or copolymers, comprising reacting ethylene and optionally one or more comonomers at a high pressure, conveniently between 1600 and 4000 kg/cm , and at temperatures of about 150-330&deg; C. in a reactor system consisting of at least one autoclave reactor or of a combination of autoclave and tubular reactors, in the presence of free radical initiators and a carbonyl group containing compound. Finally, the invention relates to carbonyl group containing chain transfer agents to obtain improved polymer processing and performance properties in flat die extrusion processes and applications.

Medium density ethylene polymers, a process to prepare these polymers and use of carbonyl group containing chain transfer agents in this process

Growing community of inventors

Terneuzen, Netherlands

Juan Manuel Mezquita