Polyethylene Composition with Bicycloheptane Salt Nucleating Agent
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Solution Overview
Problem
There is a need for combinations of polymer and nucleating agent that exhibit favorable nucleation and yield polymer compositions with desirable physical properties, such as lower water vapor and oxygen transmission rates, for applications like injection molding and cast film processes.
Innovation Solution
A thermoplastic polymer composition comprising a polyethylene polymer with a Melt Relaxation Product (MRP) of ≤ 50,000 and a salt of bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, which is used to produce injection molded articles and films through specific processing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a nucleating agent is used to improve crystallization rate and reduce cycle time, then productivity is improved, but selecting the appropriate nucleating agent becomes complex due to interrelationships between multiple polymer physical properties
Solution Approach 1:
The patent changes the parameter of nucleating agent selection from a complex multi-property matching problem to a simple MRP value-based selection. By defining MRP as a single composite parameter that captures the essential interrelationships between polymer properties (molecular weight, branching, comonomer content), the patent enables straightforward selection of appropriate nucleating agents without needing to analyze multiple interacting properties simultaneously.
Solution Approach 2:
The patent creates a composite concept by combining multiple polymer physical properties into a single MRP parameter. This composite parameter integrates molecular weight, molecular weight distribution, branching content, and comonomer content into one value that predicts nucleating agent effectiveness, simplifying the selection process while maintaining accuracy.
2Ease of manufacture
If conventional nucleating agents are used without considering polymer physical properties, then ease of manufacture is improved, but the resulting polymer composition fails to achieve desired barrier properties
Solution Approach 1:
The patent transforms the manufacturing approach from simple addition of any nucleating agent to selection based on MRP parameter matching. This parameter-based selection ensures that the nucleating agent is appropriately matched to the polymer's physical properties, guaranteeing desired barrier properties while maintaining ease of manufacture through straightforward MRP calculation and comparison.
3Strength
If the polymer has high molecular weight and narrow molecular weight distribution for improved mechanical strength, then strength is improved, but melt relaxation is reduced which decreases nucleating agent effectiveness
Solution Approach 1:
The patent resolves this contradiction by incorporating molecular weight and molecular weight distribution into the MRP parameter definition. High molecular weight polymers with narrow distributions can achieve both strength and effective nucleation because their specific MRP values indicate appropriate melt relaxation characteristics. The MRP parameter captures the nuanced relationship between molecular weight properties and nucleation effectiveness.
Solution Approach 2:
The patent creates a composite parameter that integrates strength-related properties (molecular weight) with nucleation-related properties (melt relaxation). The MRP parameter combines these seemingly contradictory requirements into a single metric that identifies polymers achieving both mechanical strength and effective nucleation through appropriate molecular weight characteristics.
4Adaptability or versatility
If multiple polymer properties are optimized independently for different applications, then adaptability is improved, but the complexity of identifying appropriate nucleating agent pairings increases
Solution Approach 1:
The patent creates a universal MRP parameter that serves multiple functions: it characterizes polymer physical properties, predicts nucleating agent effectiveness, and guides nucleating agent selection across different applications. This single parameter works universally for various polymer types (polyethylene, polypropylene, polystyrene) and applications (injection molding, extrusion, blow molding), eliminating the need for separate optimization approaches for each application.
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 described composition achieves significantly lower water vapor and oxygen transmission rates compared to unnucleated or poorly nucleated polymers, making it suitable for applications requiring improved barrier properties.
Implementation Method 1
These nucleating agents generally function by forming nuclei or providing sites for the formation and/or growth of crystals in the thermoplastic polymer as it solidifies from a molten state
Implementation Method 2
heating the thermoplastic polymer composition to a temperature sufficient to melt the thermoplastic polymer composition so that it may be injected into a mold
Implementation Method 3
allowing the molten thermoplastic polymer composition in the mold cavity to cool and solidify thereby forming an injection molded article
Implementation Method 4
passing the film exiting the die orifice over a cooled surface to solidify the thermoplastic polymer composition
Data Source
AI summary
A thermoplastic polymer composition comprises a polyethylene polymer composition and a salt of bicyclo[2.2.1]heptane-2,3-dicarboxylic acid. The polyethylene polymer composition can have a Melt Relaxation Product of 50,000 or less. A method for producing an injection molded article comprises the steps of (a) providing a thermoplastic polymer composition as described above, (b) melting the thermoplastic polymer composition, (c) injecting the molten thermoplastic polymer composition into a mold cavity, (d) cooling the molten thermoplastic polymer composition, and (e) ejecting the injection molded article from the mold cavity. A method for producing a film comprises the steps of (a) providing a thermoplastic polymer composition as described above, (b) melting the thermoplastic polymer composition, (c) extruding the molten thermoplastic polymer composition through a slot-shaped die orifice to form a film, (d) cooling the film, and (e) collecting the film.