High Pressure Polyethylene Polymerization Using Cobalt Catalyst
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Solution Overview
Problem
High pressure polymerization processes for polyethylene typically result in low-density polyethylene, which is not suitable for specific applications requiring higher density.
Innovation Solution
The process involves using a cobalt containing complex as a catalytic chain transfer agent within the high pressure polymerization process, operating at temperatures between 150°C and 330°C and pressures between 150 MPa and 400 MPa, to achieve polyethylene with a density higher than 930 kg/m³, preferably in a tubular reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional high pressure polymerization process is used, then polyethylene is produced, but the density is low (not suitable for applications requiring higher density)
Solution Approach 1:
The patent applies parameter changes by introducing a cobalt containing complex as a catalytic chain transfer agent, which fundamentally alters the polymerization mechanism. This changes the molecular structure of the polyethylene by controlling chain growth and branching, thereby increasing the density from conventional low-density values to 930-985 kg/m³, making it suitable for applications requiring higher density materials.
2Manufacturing precision
If high pressure polymerization is used to produce polyethylene, then production is achieved, but chain branching is high resulting in low density
Solution Approach 1:
The cobalt containing complex acts as an intermediary substance that mediates the polymerization process. It functions as a catalytic chain transfer agent that controls the growth of polymer chains and reduces chain branching. The complex facilitates controlled chain transfer reactions, resulting in polyethylene with reduced branching and increased density while maintaining the high-pressure polymerization process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method produces polyethylene with a density ranging from 930 to 985 kg/m³ and a narrow molecular weight distribution, achieving high density with low chain branching and Mw/Mn lower than 10, suitable for various applications.
Implementation Method 1
The process involves using a cobalt containing complex as a catalytic chain transfer agent within the high pressure polymerization process
Implementation Method 2
During the polyethylene high-pressure process polyethylene is prepared by radical polymerisation in supercritical ethylene
Implementation Method 3
polyethylene is prepared by radical polymerisation in supercritical ethylene
Implementation Method 4
which is provided on the outside with a jacket through which cooling water flows in order to remove the developed heat of reaction via the wall
Data Source
AI summary
The invention relates to a high pressure polymerisation process for the preparation of the polyethylene wherein the polymerisation process takes place in the presence of a cobalt containing complex. The cobalt containing complex may be a complex according to Formula (I): Formula (I) wherein y1, y2, y3 and y4 may, independently of one another be the same or different, H, (C1C20) alkyl, (C5-C20) cycloalkyl, (C6-C10) aryl radical, phenyl or hydroxy-phenyl.