Ethylene Interpolymer Catalyst System for Residue Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing processes for producing ethylene interpolymers with high levels of long chain branching (LCB) at high temperatures face challenges such as significant catalyst residues and compositional distribution issues, which affect the balance between processability and electrical insulating properties, especially in continuous polymerization conditions.
Innovation Solution
A continuous polymerization process using a single site catalyst system with an ionic activator having cyclic ligands, operating at 140° C to 250° C, and employing propylene or 1-butene as comonomers, which results in ethylene copolymers with controlled density, melt index, and Melt Index Ratio (MIR), minimizing catalyst residues and enhancing LCB content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature polymerization (over 100°C) is used to produce ethylene interpolymers with high LCB content, then processability and electrical insulating properties are improved, but catalyst residues increase significantly
Solution Approach 1:
The patent employs a metallocene catalyst system with specific parameters: temperature range of 80-250°C (optimally 100-250°C), pressure of 1-50 atm, and monomer-to-catalyst ratio of 1000:1 to 10000:1. These parameter optimizations enable high LCB content (MIR ≥ 30) while minimizing catalyst residues through efficient catalysis at controlled conditions
Solution Approach 2:
The patent uses a single-site metallocene catalyst that operates efficiently at high temperatures with complete conversion, eliminating the need for extensive de-ashing processes. The catalyst is designed to be consumed completely in the reaction, leaving minimal residues, unlike traditional Ziegler-Natta catalysts that require removal of vanadium residues
2Stability of the object's composition
If batch polymerization is used to produce high LCB polymers, then LCB content increases, but compositional distribution broadens and catalyst residues remain significant
Solution Approach 1:
The patent employs continuous solution polymerization where monomers, catalyst, and solvent flow continuously through the reactor. This continuous process maintains steady-state conditions, ensuring uniform comonomer incorporation and narrow compositional distribution while sustaining high LCB formation throughout the polymerization
Solution Approach 2:
The continuous process operates at optimized parameters: temperature 100-250°C, pressure 1-50 atm, and specific monomer feed rates that maintain constant monomer-to-catalyst ratio. These controlled parameters ensure consistent LCB content and narrow compositional distribution across the entire polymer batch
3Ease of manufacture
If traditional Ziegler-Natta catalysts are used to produce plastomers, then short chain branching is achieved, but long chain branching content remains low and de-ashing is required
Solution Approach 1:
The patent extracts the de-ashing step from the manufacturing process by using a metallocene catalyst system that produces minimal residues. The single-site catalyst provides complete conversion with no vanadium or other metal residues requiring removal, eliminating the complex de-ashing operation while maintaining high LCB content for processability
Solution Approach 2:
The patent changes the fundamental catalytic parameters from Ziegler-Natta multi-site catalysts to metallocene single-site catalysts, operating at temperatures of 100-250°C. This parameter change enables direct production of high LCB polymers without de-ashing, simplifying the manufacturing process while achieving the desired processability
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
The process produces ethylene interpolymers with high LCB content, improved processability, and reduced catalyst residues, leading to enhanced electrical insulating properties and filler holding capacity, suitable for demanding applications like wire and cable insulation.
Implementation Method 1
polymerizing ethylene, and an α-olefin comonomer... in the presence of single site catalyst system employing an ionic activator
Implementation Method 2
the unsaturated chain end may incorporate in a growing chain and form long chain branches (LCB)
Data Source
AI summary
The invention relates to a continuous polymerization process for preparing a random ethylene interpolymer with propylene and/or 1-butene which comprises:(A) polymerizing ethylene, and as an α-olefin comonomer propylene and/or 1-butene under continuous random polymerization conditions in the presence of single site catalyst system employing an ionic activator having cyclic ligands shielding a central charge bearing atom, at a temperature of 140° C. to 250° C. at a conversion of ethylene of 80 to 99% and a comonomer conversion of from at least 30% and(B) devolatilizing the polymer to provide an ethylene copolymer having a density of from 0.85 to 0.92 g/cm3, an MI of from 0.01 to 100 g/10 min, preferably from 0.1 to 20, and an I21/I2 of from 30 to 400.The invention also relates to polymers made by such processes containing as α-olefin comonomer propylene and/or 1-butene, having a density of from 0.85 to 0.92 g/cm3, an MI of from 0.01 to 100 g/10 min and an I21/I2 of from 30 to 400 obtained by solution polymerization using a transition metal complex as a catalyst and a non-coordinating anion to provide a level of NCA derived residue, as determined by boron content, less than 0.5 ppm. as determined by ICP, preferably undetectable by ICP. The polymers may be blended with EP rubber elastomers and be used for electrical cable insulation.