Biaxially Oriented Polyester Film with Peelable Polypropylene Sacrificial Layer
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Solution Overview
Problem
Existing biaxially oriented polyester films require a smooth and clean surface for applications like OLEDs and LCDs, but existing sacrificial layers like EMAA are expensive, prone to clogging, and cause corrosion, while attempts with polyolefin layers have been unsuccessful.
Innovation Solution
A co-extruded biaxially oriented film with a removable polypropylene layer containing at least 80% polypropylene, which is durable, inexpensive, and can be processed at high temperatures without decomposing, applied to a polyester layer with aliphatic diols and aromatic dicarboxylic acids, allowing for a smooth and clean surface after removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EMAA is used as a sacrificial layer to provide a smooth and clean surface, then the surface quality is improved, but the cost increases and the extrusion dies become clogged
Solution Approach 1:
The patent replaces expensive EMAA with polypropylene as a disposable sacrificial layer. The polypropylene layer is applied, serves its protective function during processing, and is then removed and discarded, eliminating the need for expensive materials while solving the clogging issue through polypropylene's resistance to die blockage.
Solution Approach 2:
The patent extracts the problematic properties of EMAA (expensiveness, clogging, corrosion) by removing it from the system and replacing it with polypropylene. The sacrificial layer function is maintained but the material composition is changed to eliminate the harmful characteristics while preserving the protective function.
2Object-affected harmful factors
If EMAA is used as a sacrificial layer to protect the polyester surface, then the surface protection is improved, but corrosion of equipment occurs
Solution Approach 1:
The patent uses polypropylene as a disposable protective layer that does not corrode equipment. Unlike EMAA, polypropylene is chemically inert and does not generate acid that would corrode metal dies and equipment, thus eliminating the harmful effect while maintaining protection.
Solution Approach 2:
The patent converts the potential harm of needing a protective layer into a benefit by using polypropylene, which provides protection without causing corrosion. The material's chemical inertness transforms a potential problem (protection requirement) into a solution that eliminates equipment corrosion.
3Ease of manufacture
If polyolefin layers are used as sacrificial layers to reduce cost, then the expense is reduced, but the layers cannot be removed successfully
Solution Approach 1:
The patent changes the material parameters by using polypropylene with specific properties (molecular weight, crystallinity, surface energy) that enable successful removal. The parameter optimization ensures that the polypropylene layer adheres sufficiently during processing but removes cleanly afterward, solving the removal problem while maintaining low cost.
4Strength
If the polyester film is processed at high temperatures to improve properties, then the mechanical and optical properties are improved, but the film may decompose
Solution Approach 1:
The patent uses polypropylene as a temporary protective layer that can withstand high processing temperatures without decomposing. This allows the polyester film to be processed at optimal temperatures for improving mechanical and optical properties while the polypropylene layer remains stable and protects the surface.
Solution Approach 2:
The patent applies the polypropylene layer beforehand to cushion or protect the polyester surface during high-temperature processing. The polypropylene acts as a protective barrier that prevents direct exposure to conditions that might degrade the polyester, allowing safe high-temperature processing.
Data Source
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AI summary
The present invention relates to a co-extruded, biaxially oriented film comprising at least one polyester layer, wherein a peelable polypropylene layer is applied to at least one of the two surfaces of the polyester layer and can be peeled off the polyester layer without leaving any residue. The polypropylene layer contains at least 80 wt.% polypropylene, and the polyester layer contains at least 50 wt.% of a polyester comprising aliphatic diols and aromatic dicarboxylic acids as monomers. The present invention further relates to methods for producing such a film. After removal of the polypropylene layer, the film can be used as a substrate for a high-barrier film.