Formable Biaxially-Oriented Polyester Film
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Solution Overview
Problem
Current biaxially-oriented polyester films lack sufficient formability and moisture barrier properties, limiting their use in flexible packaging and balloon applications, where higher formability and extended floating time are required.
Innovation Solution
Development of a formable biaxially-oriented film comprising a crystalline polyester layer with a formability enhancer, which has a melting point less than 230°C, and an optional amorphous copolyester layer, enhancing polymeric chain flexibility and reducing Young's Modulus, thereby improving stretchability and moisture barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline polyester film is used to provide moisture barrier properties, then moisture barrier performance is improved, but formability and stretchability deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of crystalline polyester (for moisture barrier) combined with formability enhancers having lower melting points (such as amorphous polyester or copolyester components). This composite structure allows the film to maintain high moisture barrier properties from the crystalline polyester while gaining improved formability and stretchability from the formability enhancer that melts at lower temperatures during forming operations.
2Stability of the object's composition
If crystalline polyester film is used to maintain dimensional stability, then structural integrity is improved, but resistance to stretching increases
Solution Approach 1:
The patent changes the thermal parameters of the film by incorporating formability enhancers with melting points below 230°C. During the forming process, the film is heated to a temperature range that melts these enhancers but maintains the crystalline polyester structure. This parameter change temporarily reduces the resistance to stretching during forming, while the crystalline polyester ensures dimensional stability is restored after cooling.
3Ease of operation
If formability enhancer with melting point less than 230°C is added to crystalline polyester, then polymeric chain flexibility is improved, but Young's Modulus decreases
Solution Approach 1:
The patent exploits phase transitions of the formability enhancer components that melt at temperatures below 230°C. During forming operations, heating induces melting of these enhancers, creating a more flexible polymeric chain structure with reduced Young's Modulus that facilitates easy forming. After cooling, the enhancers solidify again, restoring sufficient structural strength while maintaining the flexibility gained during processing.
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 lower resistance to stretching, a softer feel, and enhanced moisture barrier properties, allowing for more intricate shapes and extended floating times in balloon applications while maintaining dimensional stability and puncture resistance.
Implementation Method 1
The formability enhancer has a melting point less than about 230° C.
Implementation Method 2
The first layer comprises from about 10 to about 90 wt. % crystalline polyester
Data Source
AI summary
A formable biaxially-oriented film includes a first layer. The first layer includes from about 10 to about 90 wt. % crystalline polyester and from about 10 to about 90 wt. % of a formability enhancer to assist in increasing the polymeric chain flexibility. The formability enhancer has a melting point less than about 230° C. The film has a MD and a TD Young's Modulus of at least 10% lower than a crystalline polyester film in the absence of the formability enhancer. The film may further include a second layer, which includes an amorphous copolyester. The second layer may be adjacent to or attached to the first layer.