Thermo-shrinkable Polyester Film Molecular Orientation Control
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Solution Overview
Problem
Conventional thermo-shrinkable polyester films face issues with uneven shrinkage, crinkling, edge curling, and fragility, which affect their practical use and appearance when used for labeling and packaging, particularly during high-speed thermo-shrinkage processes.
Innovation Solution
A thermo-shrinkable polyester film with a molecular chain orientation angle between 0° to ±10° relative to the main shrinkage direction and a molecular orientation ratio (MOR) between 1.29 and 2.5, achieved through extrusion and uniaxial stretching, followed by heat treatment, to ensure stable and uniform shrinkage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polyester film is used for thermo-shrinkage, then heat resistance and weatherability are improved, but the film becomes fragile and cracks easily during high-speed thermo-shrinkage or transportation
Solution Approach 1:
The patent changes the molecular orientation parameters of the polyester film by controlling the stretching process. Specifically, it sets the molecular chain orientation angle to 0° to ±10° relative to the main shrinkage direction and the molecular orientation ratio (MOR) to 1.29-2.5. This parameter optimization allows the film to maintain heat resistance while reducing fragility during thermo-shrinkage and transportation.
2Reliability
If conventional polyester film undergoes high-temperature sterilization after shrinking, then sterilization is achieved, but the strength of the film is lowered
Solution Approach 1:
The patent performs preliminary molecular orientation control during the stretching process before sterilization. By optimizing the molecular chain arrangement (orientation angle 0° to ±10° and MOR 1.29-2.5) in advance, the film structure is pre-conditioned to withstand high-temperature sterilization without significant strength loss.
3Productivity
If conventional thermo-shrinkable film is used, then basic packaging function is achieved, but uneven shrinkage and crinkling occur during high temperature quick shrinking process
Solution Approach 1:
The patent optimizes molecular orientation parameters to achieve uniform shrinkage. By controlling the molecular chain orientation angle to 0° to ±10° and MOR to 1.29-2.5, the film exhibits consistent shrinkage behavior during high-temperature quick shrinking, eliminating crinkling and edge curling while maintaining high productivity.
4Stability of the object's composition
If poly(vinyl chloride) or polystyrene is used for thermo-shrinkage film, then thermo-shrinkability is achieved, but heat resistance and chemical resistance are insufficient
Solution Approach 1:
The patent uses polyester as the base material, which inherently provides excellent heat resistance and chemical resistance. By optimizing the molecular orientation of this polyester material rather than using composite formulations, the film achieves both thermo-shrinkability and superior thermal/chemical stability.
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 a stable thermo-shrinkage mainly in the main direction, preventing curling or waving of labels and maintaining rigid packing conditions, while minimizing shrinkage in perpendicular directions, thus enhancing the film's usability and appearance.
Implementation Method 1
a rotation angle (θ) at which a microwave transmit intensity, I(θ), has a maximum value
Implementation Method 2
the interaction between molecular dipole moment and polarized microwave in a sample film
Implementation Method 3
thermo-shrinkable polyester film
Data Source
AI summary
The present invention relates to a thermo-shrinkable polyester film with a superior thermal shrinkage, which has an orientation angle of a molecular chain in a range of from 0° to about ±10° relative to a main shrinkage direction, and a molecular orientation ratio (MOR) in a range of from 1.29 to about 2.5, thereby preventing a label made from the film from curling or waving.