Multilayer Biaxially Oriented Polyester Film for Low-Temperature Sealing
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Solution Overview
Problem
Conventional biaxially oriented PET films suffer from drawbacks such as non-sealability, poor mechanical strength, inadequate barrier properties, and poor dimensional stability, making them unsuitable for high-temperature applications and recyclability.
Innovation Solution
A biaxially oriented sealable and non-sealable polyester film with a multilayer structure B/B/A, comprising outer and middle layers with thermoplastic polyethylene terephthalate (PET) and modified PET polymers, and an inner layer with PET, MBUV, or SH3-M polymer, enhancing mechanical strength, sealability, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional biaxially oriented PET films are used, then manufacturing simplicity is maintained, but sealability is poor and mechanical strength is inadequate
Solution Approach 1:
The patent employs a multilayer composite structure combining different PET variants (standard PET, modified PET with isophthalic acid, and crystallizable PET) to achieve superior mechanical strength and sealability. Each layer contributes specific properties: standard PET provides structural integrity, modified PET enhances sealability at lower temperatures, and crystallizable PET improves thermal stability, collectively resolving the contradiction between strength and structural complexity.
Solution Approach 2:
The film is divided into multiple functional layers with distinct compositions and properties. The segmentation allows each layer to perform its specific function optimally while contributing to the overall mechanical strength, thereby achieving high performance without requiring excessive complexity in any single layer.
2Stability of the object's composition
If conventional PET films are used, then processing simplicity is maintained, but dimensional stability at high temperature is poor
Solution Approach 1:
The incorporation of crystallizable PET in the multilayer structure provides excellent dimensional stability at high temperatures due to its higher crystallization temperature and melting point. This composite approach maintains stability without requiring overly complex processing equipment, as the enhanced properties arise from material composition rather than complex device architecture.
3Reliability
If conventional PET films are used, then manufacturing cost is low, but barrier properties are inadequate
Solution Approach 1:
The multilayer composite structure with modified PET layers provides enhanced barrier properties against moisture and oxygen transmission. The different PET variants create a more effective barrier system compared to conventional single-layer PET, achieving improved reliability without requiring complex external barrier coatings or structures.
4Strength
If conventional PET films are used, then simplicity is maintained, but seal strength is poor and seal initiation temperature is high
Solution Approach 1:
The modified PET layer containing isophthalic acid units provides lower seal initiation temperature and enhanced seal strength. The compositional modification allows sealing to occur at lower temperatures compared to conventional PET, while the multilayer structure ensures strong adhesion and seal integrity, resolving the contradiction between seal strength and temperature requirements.
Data Source
AI summary
The present invention relates to a biaxially oriented sealable and non-sealable polyester film of multilayer structure B/B/A comprising: (a) an outer layer B; (b) a middle layer B; and (c) an inner layer A. The present invention also relates to a process for preparing the biaxially oriented sealable polyester film as described herein. The biaxially oriented and non-sealable flexible polyester film of the present invention an enhanced mechanical properties i.e. tensile, elongation, dart impact, tear resistance, with better drawability, high temperature stability and high seal strength low seal initiation temperature.