Polyester Sealant Film with Low Crystallinity for Packaging
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Solution Overview
Problem
Existing sealant films used in packaging materials suffer from inadequate tensile elongation, heat sealability, non-adsorptivity, and gas barrier properties, particularly when made from polyolefins, which can lead to issues with odor absorption and contamination.
Innovation Solution
A sealant film comprising a polyester with 20-50 mol% 2,5-furandicarboxylic acid units, 18-49.5 mol% diol units (ethylene glycol, 1,3-propanediol, or 1,4-butanediol), and 0.5-2.5 mol% diethylene glycol units, with a crystallinity of less than 14% and a shrinkage ratio of 6% or more upon heating, achieved through extrusion-molding and uniaxial or biaxial stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefins are used as sealant film material, then ease of manufacture is improved, but non-adsorptivity and gas barrier properties deteriorate due to odor absorption and contamination
Solution Approach 1:
The patent changes the chemical composition parameters of the sealant film by using polyesters (PET, PEF, PBT) instead of polyolefins. This material substitution fundamentally alters the chemical structure to reduce adsorption of organic compounds while maintaining manufacturability through established polyester processing techniques
Solution Approach 2:
The patent employs composite polyester structures with specific compositions (PET/PEF/PBT combinations) to achieve both non-adsorptivity and gas barrier properties. The composite nature of these polyesters provides enhanced performance compared to single-material approaches
2Object-affected harmful factors
If existing polyester compositions are used, then non-adsorptivity is improved, but tensile elongation deteriorates
Solution Approach 1:
The patent optimizes the crystallinity parameter of the polyester to be 10% or less, which fundamentally changes the mechanical properties. This low crystallinity parameter achieves both non-adsorptivity and improved tensile elongation (150% or more) simultaneously, resolving the contradiction between these two properties
3Strength
If sealant film with improved mechanical properties is produced, then tensile elongation is improved, but heat sealability deteriorates
Solution Approach 1:
The patent precisely controls the crystallinity parameter at 10% or less, which creates an optimal balance between mechanical properties and heat sealability. This parameter optimization allows the film to achieve high tensile elongation while maintaining reliable heat sealing performance
Solution Approach 2:
The patent creates different local properties within the sealant film structure - the amorphous regions provide tensile elongation and flexibility, while the crystalline regions maintain heat sealability. This local quality differentiation resolves the contradiction between these two requirements
4Object-affected harmful factors
If polyester composition is optimized for non-adsorptivity, then gas barrier properties are improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses the crystallinity parameter as a key control variable, setting it at 10% or less. This parameter change simultaneously improves gas barrier properties (through the polyester material selection) and mechanical strength (through the low crystallinity structure), eliminating the trade-off between these properties
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 resulting sealant film exhibits superior mechanical properties, tensile elongation, heat sealability, and non-adsorptivity, making it suitable for use as an innermost layer in various packaging materials while maintaining excellent gas barrier properties.
Implementation Method 1
the sealant film is a stretched film that exhibits a shrinkage ratio of 6% or more in a maximum shrinkage direction upon being allowed to stand at 125° C. for 20 seconds
Implementation Method 2
the sealant film is a stretched film that exhibits a shrinkage ratio of 6% or more in a maximum shrinkage direction upon being allowed to stand at 125° C. for 20 seconds
Data Source
AI summary
Disclosed is a sealant film including at least a layer formed of a polyester as a superficial layer, in which the polyester contains 20 to 50 mol % of a 2,5-furandicarboxylic acid unit, 18 to 49.5 mol % of at least one diol unit selected from the group consisting of an ethylene glycol unit, a 1,3-propanediol unit, and a 1,4-butanediol unit, and 0.5 to 2.5 mol % of a diethylene glycol unit, the sealant film has a crystallinity of less than 14%, and the sealant film is a stretched film that exhibits a shrinkage ratio of 6% or more in a maximum shrinkage direction upon being allowed to stand at 125° C. for 20 seconds. This provides a sealant film superior in mechanical properties, especially tensile elongation, and also superior in heat sealability, non-adsorptivity, and gas barrier properties.