Mixed Selectivity Catalyst for High Melt Flow Propylene
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The production of high stiffness propylene-based polymers with high melt flow rates is hindered by the excessive heat generated during polymerization, which poses a risk to reactor operability and can lead to disruptions or shutdowns.
Innovation Solution
A catalyst composition comprising a procatalyst, cocatalyst, and a mixed external electron donor (M-EED) with specific selectivity control agents and an activity limiting agent, which self-limits the polymerization reaction, allowing for the production of propylene-based polymers with high melt flow rates and stiffness under standard conditions without excessive heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If catalyst compositions with mixed selectivity control agents are used to produce high stiffness propylene-based polymers with high melt flow, then the polymer properties are improved, but the excessive heat generated during polymerization increases the risk of reactor disruption or shutdown
Solution Approach 1:
The patent introduces an activity limiting agent that changes the kinetic parameters of the polymerization reaction. This agent modifies the reaction rate and heat generation characteristics, allowing the reaction to proceed at conditions that produce high stiffness/high melt flow polymers while controlling the exothermic heat release to prevent reactor disruption or shutdown
Solution Approach 2:
The activity limiting agent acts as an intermediary substance between the catalyst system and the polymerization reaction. It mediates the interaction by controlling the reaction rate and heat generation, enabling the production of polymers with desired properties while protecting reactor operability from excessive heat effects
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 catalyst composition effectively reduces the risk of reactor disruptions by self-limiting the polymerization reaction, producing propylene-based polymers with high melt flow rates and stiffness while maintaining standard hydrogen levels and avoiding visbreaking, resulting in polymers with improved properties such as high final melting point, low oligomer content, and reduced toxicity and odor.
Implementation Method 1
contacting propylene and optionally at least one other olefin with a catalyst composition in a polymerization reactor under polymerization conditions
Implementation Method 2
The excessive heat generated during polymerization poses a significant risk to the polymerization reactor operability
Implementation Method 3
The M-EED includes an activity limiting agent (ALA), a first selectivity control agent (SCA1), a second selectivity control agent (SCA2)
Data Source
AI summary
The present disclosure provides a Ziegler-Natta catalyst composition comprising a procatalyst, a cocatalyst and a mixed external electron donor comprising a first selectivity control agent, a second selectivity control agent, and an activity limiting agent. A polymerization process incorporating the present catalyst composition produces a high-stiffness propylene-based polymer with a melt flow rate greater than about 50 g/10 min. The polymerization process occurs in a single reactor, utilizing standard hydrogen concentration with no visbreaking.