Polyester Film Heat Resistance via Isosorbide Diol Composition
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Solution Overview
Problem
Polyethylene terephthalate (PET) films suffer from low heat resistance and adhesion issues due to high crystallinity and low glass transition temperature, leading to defects in high-temperature processing and poor heat sealability, which complicates applications requiring transparency and chemical resistance.
Innovation Solution
A polyester film with a resin layer composed of a polyester resin containing isosorbide and cyclohexanedimethanol diol moieties, stretched in at least one direction, achieving improved heat resistance and adhesion by controlling the diol content and crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If PET film is heat set at high temperature to increase heat resistance, then heat resistance is improved, but oligomers precipitate and crystallize on the surface causing transparency deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester resin by incorporating specific diol moieties (1,4-cyclohexanedimethanol at 5-20 mol% and 1,3-propanediol at 5-20 mol%) to modify the polymer structure. This compositional parameter change raises the glass transition temperature and suppresses oligomer crystallization at high temperatures, allowing the film to maintain transparency while achieving heat resistance through heat setting processes.
Solution Approach 2:
The patent creates a composite polyester resin system by combining multiple diol components (1,4-cyclohexanedimethanol, 1,3-propanediol, and other diols) with dicarboxylic acid components. This composite material approach synergistically improves heat resistance through elevated glass transition temperature while maintaining clarity by preventing oligomer precipitation, resolving the contradiction between heat resistance and transparency.
2Productivity
If molding process such as printing is performed at high temperature to improve productivity, then productivity is improved, but defects occur due to low glass transition temperature of PET
Solution Approach 1:
The patent modifies the glass transition temperature parameter of the polyester resin from 80°C or lower (conventional PET) to above 80°C by incorporating 1,4-cyclohexanedimethanol and 1,3-propanediol moieties. This parameter change enables high-temperature molding and printing processes to be performed without causing defects, thereby improving productivity while maintaining reliability.
3Strength
If PET film has high crystallinity to improve mechanical properties, then mechanical strength is improved, but heat sealability deteriorates
Solution Approach 1:
The patent changes the molecular structure parameters by incorporating 1,3-propanediol and 1,4-cyclohexanedimethanol moieties that disrupt the regularity of the polymer chain. This structural parameter change reduces crystallinity while maintaining mechanical strength through the inherent properties of the cyclic diol components, thereby improving heat sealability without sacrificing mechanical performance.
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 film exhibits excellent heat resistance and adhesion, suitable for industrial, packaging, and optical applications, with enhanced heat sealability and chemical resistance.
Implementation Method 1
PET exhibits high crystallinity, especially in biaxial stretching, and thus has a disadvantage in heat sealability
Data Source
AI summary
The present disclosure relates to a polyester film and a preparation method of the same. Since the polyester film includes a resin layer formed from a polyester resin including a first diol moiety derived from isosorbide and a second diol moiety derived from cyclohexanedimethanol in a controlled ratio on at least one surface of a base layer, it is possible to exhibit excellent heat resistance and adhesion.