Ethylene Polymer Blend for Film Neck-In Control
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Solution Overview
Problem
Ethylene polymers used in film formation with T-die experience issues like neck-in and surging, leading to uneven thickness and mechanical strength challenges, while existing solutions compromise on mechanical strength or formability.
Innovation Solution
A specific ethylene polymer composition comprising two copolymers with defined melt flow rates, branch densities, and viscosity ratios, which when blended, enhance melt tension and strain hardening, reducing neck-in and surging, and providing excellent mechanical strength and blocking resistance without the need for anti-blocking agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure low density polyethylene is used to improve melt tension and reduce neck-in, then formability is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of metallocene ethylene polymer and high pressure low density polyethylene in specific proportions (metallocene polymer 30-70 wt%, HPLDE 30-70 wt%). This composite approach allows the metallocene polymer to provide mechanical strength while the HPLDE component provides high melt tension and reduced neck-in, resolving the contradiction between formability and mechanical strength
Solution Approach 2:
The patent optimizes the composition ratio parameters of the two polymers, specifically setting the metallocene ethylene polymer content at 30-70 wt% and HPLDE at 30-70 wt%. This parameter optimization ensures that the blend achieves both high melt tension (improved formability) and sufficient mechanical strength, resolving the trade-off between these properties
2Strength
If metallocene ethylene polymer is used to improve mechanical strength, then tensile and tear strength are enhanced, but melt tension decreases causing large neck-in
Solution Approach 1:
The patent creates a composite blend where metallocene ethylene polymer (providing high tensile and tear strength) is combined with high pressure low density polyethylene (providing high melt tension). The synergistic effect of this composite allows simultaneous achievement of both mechanical strength and good neck-in control that neither polymer can achieve alone
3Manufacturing precision
If high pressure low density polyethylene is used to reduce surging, then film thickness uniformity is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent employs a composite blend where HPLDE provides the strain hardening property that suppresses surging and ensures uniform film thickness, while metallocene ethylene polymer compensates for the mechanical strength deficiency. This composite approach allows simultaneous achievement of thickness uniformity and mechanical strength
4Manufacturing precision
If excessive amount of high pressure low density polyethylene is used to improve formability, then neck-in and surging are reduced, but mechanical strength deteriorates
Solution Approach 1:
The patent precisely controls the composition ratio parameter, specifying metallocene ethylene polymer at 30-70 wt% and HPLDE at 30-70 wt%. This optimized parameter range ensures sufficient HPLDE content for good formability (reduced neck-in and surging) while maintaining adequate metallocene polymer content for mechanical strength, resolving the contradiction through parameter optimization
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 ethylene polymer composition achieves high formability, mechanical strength, and excellent blocking resistance, improving film production yield and quality by minimizing neck-in and surging, and eliminating the need for anti-blocking agents.
Implementation Method 1
strain hardening in elongation viscosity is enhanced by increase in a strain rate
Implementation Method 2
strain hardening in elongation viscosity is enhanced by increase in a strain rate
Data Source
AI summary
The present invention provides an ethylene polymer composition having a particularly high formability and having an excellent mechanical strength, a shaped article formed of such an ethylene polymer, and a film and multilayer film having a particularly excellent blocking resistance. An ethylene polymer composition (γ) according to the present invention includes a specific ethylene polymer (α) that is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and an ethylene polymer (β) that is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms but different from the ethylene polymer (α), and weight fraction [Wα] of the ethylene polymer (α) is in the range of not less than 0.1 and not more than 0.9, and weight fraction [Wβ] of the ethylene polymer (β) is in the range of not less than 0.1 and not more than 0.9 (the sum of the Wα and the Wβ is 1.0).