Stretched Polyethylene Film for Heat-Resistant, Recyclable Lamination
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Solution Overview
Problem
Existing polyethylene films lack sufficient rigidity, heat resistance, and recyclability, making them unsuitable for certain applications and hindering effective recycling due to material incompatibilities and heat-sealing issues.
Innovation Solution
A stretched polyethylene film with specific molecular weight, density, and thermal properties, combined with an ethylene polymer film, is produced using controlled polymerization methods and further processed for biaxial stretching and optional surface treatments, resulting in a laminated film with enhanced heat resistance and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stretched polyethylene film is used to compensate for mechanical properties and suppress adhesion, then flexibility and moisture resistance are improved, but heat resistance remains insufficient and heat-sealing temperature must be lowered
Solution Approach 1:
The patent changes the molecular weight parameters of the polyethylene, specifically using weight average molecular weight (Mw) of 70,000 to 250,000 and controlling the proportion of low molecular weight fractions to 5 wt% or less. This parameter optimization enables the film to achieve both improved mechanical properties and enhanced heat resistance with elevated heat-sealing temperature, resolving the contradiction between mechanical strength and thermal performance.
2Strength
If an ultrahigh molecular weight polyethylene film is used to improve rigidity and heat resistance, then mechanical strength is enhanced, but melt-miscibility with common polyethylene deteriorates and recyclability is impaired
Solution Approach 1:
The patent optimizes the molecular weight parameters by setting weight average molecular weight (Mw) to 70,000 to 250,000 and controlling low molecular weight fractions to 5 wt% or less. This parameter range achieves the desired rigidity and heat resistance while maintaining adequate melt-miscibility with common polyethylene, thereby preserving recyclability and avoiding the problems associated with ultrahigh molecular weight polyethylene.
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 laminated film exhibits improved heat resistance and recyclability, suitable for packaging applications, with a high proportion of polyethylene content for reduced environmental impact.
Implementation Method 1
a stretched polyethylene film for lamination, which comprises a polyethylene (A) having a weight average molecular weight (Mw) as measured by gel permeation chromatography of from 70,000 to 250,000... and has at least one peak in a range of 135° C. or higher in an endothermic curve as measured by a differential scanning calorimetry
Implementation Method 2
has at least one peak in a range of 135° C. or higher in an endothermic curve as measured by a differential scanning calorimetry
Data Source
AI summary
A stretched polyethylene film for lamination, which comprises a polyethylene (A) having a weight average molecular weight (Mw) as measured by gel permeation chromatography of from 70,000 to 250,000, a proportion of fractions with a molecular weight of 10,000 or less of 8 wt % or less, and a density as measured in accordance with JIS K6922-1 (1997) of from 945 to 980 kg/m3, and has at least one peak in a range of 135° C. or higher in an endothermic curve as measured by differential scanning calorimetry, the film having high recyclability and excellent in heat resistance.