Shape-Retaining Polyethylene Film for Adhesion and Thermal Management
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Solution Overview
Problem
Existing shape-retaining films and packaging materials face challenges with adhesion issues for additional layers, insufficient shape retainability, and difficulties in processing general-purpose polyethylenes into fibers with high thermal conductivity and elasticity, while conventional heat-conductive sheets exhibit low shape retainability and risk of damaging electronic circuits.
Innovation Solution
A shape-retaining film produced by stretching polyethylene at a high stretch ratio, forming microscopic irregularities for enhanced adhesion and shape retainability, and processing general-purpose polyethylenes into fibers with high thermal conductivity and elasticity, along with anisotropic heat-conductive films for improved thermal management in electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If uniaxially-stretched polyethylene films are used as shape-retaining films, then shape retainability is improved, but adhesion for additional layers and direct printing is insufficient
Solution Approach 1:
The patent applies corona discharge treatment to the surface of uniaxially-stretched polyethylene films to modify surface properties. This treatment increases surface energy and creates micro-irregularities that enhance adhesion for additional functional layers and improve direct printing capability, while preserving the underlying molecular orientation that provides shape retainability
Solution Approach 2:
The patent creates a composite surface structure by combining the bulk polyethylene material (providing shape retention through molecular orientation) with a treated surface layer (providing adhesion and printability). The corona discharge treatment effectively creates a modified surface zone that complements the bulk material properties
2Shape
If aluminum foil is used for shape-retaining packaging bags, then shape retainability at the open end is improved, but disposal time increases and microwave oven use is impossible
Solution Approach 1:
The patent replaces permanent aluminum foil with disposable uniaxially-stretched polyethylene films that maintain shape retainability. These films are designed to be used once and then discarded with the packaging, eliminating the need for separate aluminum foil disposal and enabling microwave oven compatibility
Solution Approach 2:
The patent modifies polyethylene through uniaxial stretching to achieve molecular orientation that provides shape retainability comparable to aluminum foil. This parameter change (molecular orientation) allows the polymer to function as a permanent shape-retaining structure rather than requiring metal reinforcement
3Temperature
If heat-conductive sheets are used to conduct heat from heat sources, then thermal conductivity is improved, but shape retainability is insufficient and risk of damaging electronic circuits increases
Solution Approach 1:
The patent creates composite heat-conductive films by combining uniaxially-stretched polyethylene (providing shape retention and structural stability) with heat-conductive fillers or layers. This composite structure maintains the rigid, shape-retaining properties of oriented polyethylene while incorporating thermal conduction pathways through embedded conductive materials
Solution Approach 2:
The patent modifies the thermal conduction parameter of polyethylene through uniaxial stretching, which aligns polymer chains and creates anisotropic thermal conductivity. The stretching process itself changes the thermal transport properties by creating preferential pathways for heat conduction along the stretch direction
4Quantity of substance
If general-purpose polyethylenes are processed into fibers, then material availability is improved, but thermal conductivity and elasticity are insufficient
Solution Approach 1:
The patent applies uniaxial stretching to general-purpose polyethylene fibers to induce molecular orientation along the fiber axis. This parameter change transforms the random coil structure of unprocessed polyethylene into an aligned configuration that enhances thermal conductivity and elastic properties while maintaining compatibility with standard polyethylene materials
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 solution provides films and fibers with superior shape retainability, adhesion, and thermal conductivity, enabling effective packaging and heat dissipation without damaging electronic circuits, and allows for the use of general-purpose polyethylenes in high-performance applications.
Implementation Method 1
a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) of 5 to 20, wherein the shape-retaining film has a tensile elasticity modulus of 6 to 50 GPa, and exhibits an angle of recovery from 90° bending of 8° or less or an angle of recovery from 180° bending of 65° or less
Implementation Method 2
the anisotropic heat-conductive film conducts heat from the heat source to the heat dissipator
Data Source
AI summary
Provided are a shape-retaining film which has excellent adhesion to inks and other functional layers while retaining high shape-retaining properties and a process for producing the shape-retaining film. The shape-retaining film comprises an ethylene homopolymer or an ethylene/a-olefin copolymer having a C3-6 a-olefin content less than 2 wt. %, the ethylene homopolymer or copolymer having a density of 950 kg/m3 or higher and a weight-average molecular weight (Mw)/number-average molecular weight (Mn) ratio of 5-20. The film has a tensile elasticity modulus of 6-50 GPa and has either an angle of recovery from 90 bending of 8 or less or an angle of recovery from 180 bending of 65 or less.