Dicarbonate Internal Donors for Polypropylene Catalysts
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Solution Overview
Problem
Current propylene polymerization catalyst systems face limitations in achieving desired polymer properties such as high isotacticity, xylenes soluble fraction, and final melting temperature, while also raising environmental concerns due to the use of alkyl phthalate esters as internal electron donors.
Innovation Solution
Incorporating a solid, hydrocarbon-insoluble catalyst component containing magnesium, titanium, and a halogen, along with an internal electron donor comprising a dicarbonate structure, which acts as a selective control agent to enhance catalyst activity and polymer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkyl phthalate esters are used as internal electron donors in propylene polymerization catalyst systems, then catalyst activity and polymer production are maintained at acceptable levels, but environmental concerns arise due to human contact and health safety issues
Solution Approach 1:
The patent changes the chemical structure of the internal electron donor from conventional alkyl phthalate esters to cyclic carbonate compounds with specific molecular structures (formula I and II). This structural parameter change maintains the electron-donating functionality required for catalyst activity while eliminating the environmental and health concerns associated with phthalate derivatives. The cyclic carbonate structure provides similar electronic properties to phthalates but with improved safety and environmental profile.
2Manufacturing precision
If conventional internal electron donors are used in supported catalyst components, then catalyst system is maintained with acceptable performance, but the ability to produce polymers with high isotacticity and high melting temperature is limited
Solution Approach 1:
The patent introduces specific structural features at local positions within the cyclic carbonate molecule to control polymer properties. The formula I compounds feature specific substituent patterns on the cyclic carbonate ring that locally modify electron density and steric effects, thereby controlling isotacticity and melting temperature. The formula II compounds with bridged structures provide additional local structural control for optimizing polymer morphology and thermal properties.
Solution Approach 2:
The patent employs composite catalyst systems combining magnesium-containing supported titanium-containing catalyst components with cyclic carbonate internal electron donors. This composite approach integrates the catalytic activity of the supported titanium component with the electron-donating and structure-controlling properties of the cyclic carbonate, achieving synergistic effects that produce polymers with high isotacticity and high melting temperature simultaneously.
3Ease of manufacture
If the art uses a finite set of known compounds as internal electron donors, then catalyst preparation is simplified, but the diversity of polymer properties that can be achieved is limited
Solution Approach 1:
The patent establishes that cyclic carbonate compounds with the general formula I and II serve as universal internal electron donors that can be applied across multiple catalyst systems and polymerization conditions. These cyclic carbonates provide multi-functional benefits: electron donation for catalyst activation, structural control for isotacticity, and thermal property control for melting temperature. The versatility of this compound class allows achievement of diverse polymer properties while maintaining ease of catalyst preparation through a systematic approach.
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 use of dicarbonate-based internal electron donors in propylene polymerization catalysts improves catalyst activity, reduces small particle formation, and produces polymers with higher isotacticity and melting temperatures, addressing environmental concerns and enhancing polymer morphology.
Implementation Method 1
internal electron donor comprising a compound having a structure: [R1-O-C(O)-O-]xR2 wherein R1 is independently at each occurrence, an aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms; x is 2-4; and R2 is an aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms
Implementation Method 2
solid, transition metal-based, olefin polymerization catalyst components... magnesium-containing, titanium halide-based catalyst components
Data Source
AI summary
A solid, hydrocarbon-insoluble, catalyst component useful in polymerizing olefins, said catalyst component containing magnesium, titanium, and halogen, and further containing an internal electron donor having a structure: [R1-O-C(O)-O-]xR2 wherein R1 is independently at each occurrence, an aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms; x is 2-4; and R2 is an aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms, provided that there are from 3 to 4 atoms in the shortest chain connecting a first R1-O-C(O)-O- group and a second R1-O-C(O)-O- group.