Phthalate-Free Propylene Copolymer With High Modulus and Ductility
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Solution Overview
Problem
Existing methods for producing high impact resistant propylene polymers often require phthalate-containing catalysts, which are environmentally undesirable, and there is a need for a catalyst system that can achieve high flexural modulus and low temperature impact ductility without phthalates.
Innovation Solution
A phthalate-free catalyst system comprising magnesium halide, titanium compound with a Ti-halogen bond, electron donor compounds like urea and 1,3-diether, and optionally an external electron donor, is used to produce propylene impact copolymers through a two-stage polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phthalate-containing catalysts are used to produce high impact resistant propylene polymers, then impact resistance and low temperature ductility are improved, but environmental safety deteriorates
Solution Approach 1:
The patent removes the harmful phthalate component from the catalyst system while retaining the desired performance characteristics. The phthalate-free catalyst system (using alternative electron donors like 1,3-diether, urea, or carbonate ether) extracts the harmful element (phthalate) from the system, achieving both environmental safety and maintained impact resistance through the core catalyst components (magnesium halide and titanium compound).
Solution Approach 2:
The patent employs alternative electron donor compounds (urea, carbonate ether, 1,3-diether) that are environmentally benign and can be easily discarded or degraded, replacing the persistent and harmful phthalate compounds. These alternatives achieve the same catalytic function without the environmental persistence and toxicity issues of phthalates.
2Strength
If a two-stage polymerization process is used to achieve high flexural modulus and impact resistance, then mechanical properties are improved, but process complexity increases
Solution Approach 1:
The patent combines the catalyst preparation step with the polymerization process by incorporating electron donor compounds directly into the catalyst system. This merging of catalyst activation and polymerization functions into a unified process reduces overall process complexity while maintaining the two-stage polymerization benefits for achieving high flexural modulus and impact resistance.
Solution Approach 2:
The catalyst system designed in the patent serves multiple functions: it enables both the first-stage high crystallinity polymer formation and the second-stage copolymer formation with controlled ethylene incorporation. The universal catalyst system (magnesium halide-titanium compound-electron donor) performs multiple roles across different polymerization stages, simplifying the overall process compared to using different catalysts for each stage.
3Reliability
If ethylene content is increased to improve impact resistance, then impact resistance is improved, but flexural modulus deteriorates
Solution Approach 1:
The patent applies local quality by creating a heterogeneous polymer structure with different regions having different properties. The two-stage polymerization produces a matrix of high-crystallinity propylene polymer (providing flexural modulus) with dispersed copolymer regions containing ethylene (providing impact resistance). This spatial distribution of different polymer phases allows both properties to coexist without direct trade-off.
Solution Approach 2:
The patent creates a composite polymer material consisting of two distinct polymer phases: a crystalline propylene matrix phase (providing rigidity and flexural modulus) and an amorphous copolymer phase with ethylene units (providing impact resistance and ductility). This composite structure at the molecular level allows the material to exhibit both high flexural modulus and high impact resistance simultaneously.
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 phthalate-free catalyst system achieves high flexural modulus and low temperature impact ductility, comparable to phthalate-containing polymers, with ethylene content and impact resistance comparable to traditional methods.
Implementation Method 1
a phthalate free catalyst system comprising (a) phthalate free catalyst component obtained by contacting a magnesium halide, a titanium compound having at least a Ti-halogen bond and one or more electron donor compounds
Data Source
AI summary
The present invention provides phthalate free impact resistant polypropylene copolymer and methods of preparation, which are produced directly from the polymerization reactor system without further compounding of components which significantly alters the physical properties of the resulting polymer. The copolymer according to the present invention possesses both low temperature ductility and high flexural modulus, wherein said polymer is produced in the presence of a phthalate free ZN catalyst comprising urea component.