Co-extruded Polyester Films with Glycidyl Ester for Delamination Resistance
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Solution Overview
Problem
Multi-layer polyester films often face issues with adhesion between layers, leading to delamination when exposed to moisture or environmental conditions, which compromises their mechanical and optical properties, and existing solutions like elastomeric adhesives or intermediate tie-layers increase manufacturing complexity and may interfere with film properties.
Innovation Solution
A co-extruded multi-layer biaxially oriented polyester film is developed, where both primary and secondary layers contain a glycidyl ester of a branched monocarboxylic acid, which reacts with polyester end-groups to enhance hydrolytic stability and delamination resistance, particularly when both layers have different compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multi-layer polyester films are used to improve mechanical strength and functional properties, then the performance of the film is improved, but adhesion between layers becomes unsatisfactory leading to delamination
Solution Approach 1:
A tie-layer comprising a polycondensation product of a diol and a dicarboxylic acid is introduced between dissimilar polyester layers. This intermediary layer contains functional groups that can interact with both adjacent layers, improving adhesion and preventing delamination while maintaining the distinct properties of each layer.
Solution Approach 2:
The invention creates a composite multi-layer structure where each layer has specific functional properties. By combining different polyester types with a specialized tie-layer, the film achieves both the mechanical strength of individual layers and improved interlayer adhesion through the composite structure.
2Reliability
If intermediate tie-layers are used to improve delamination resistance, then adhesion between layers is improved, but the complexity of the film manufacturing process increases
Solution Approach 1:
The tie-layer is designed with specific compositional parameters - a polycondensation product of diol and dicarboxylic acid with controlled molecular weight and functional group content. By optimizing these parameters, the layer achieves effective adhesion without requiring complex manufacturing equipment or multi-step processes.
3Reliability
If intermediate tie-layers are used to improve adhesion, then delamination resistance is improved, but the mechanical and/or optical properties of the laminated film are interfered with
Solution Approach 1:
The tie-layer is designed to be thin and localized at the interface between dissimilar layers. Its composition is specifically tailored for adhesion function only in this localized region, while the bulk layers maintain their original mechanical and optical properties. The tie-layer's thickness and composition are optimized to provide adhesion without significantly affecting the overall film 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 film exhibits improved hydrolytic stability and delamination resistance without compromising mechanical and optical properties, maintaining ease and efficiency in manufacturing, even under humid conditions and elevated temperatures.
Implementation Method 1
the glycidyl ester is present in the form of its reaction product with at least some of the end groups of the polyester
Data Source
Figure 1
AI summary
A co-extruded multi-layer biaxially oriented polyester film comprising a primary polyester layer and a dissimilar secondary polyester layer adjacent to the primary polyester layer, wherein the primary polyester layer and the secondary polyester layer each comprise a glycidyl ester of a branched monocarboxylic acid, wherein the monocarboxylic acid has from 5 to 50 carbon atoms, and wherein said glycidyl ester is in the form of its reaction product with at least some of the end groups of the polyester; and use thereof as a component of a photovoltaic cell.