Multi-Layer Film Structure for Wet-Stable 3D Forming Modulus
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Solution Overview
Problem
Single-layer plastic films used in three-dimensionally formed articles experience a significant drop in tensile modulus when exposed to wet or humid environments, leading to instability and the need for costly reworking.
Innovation Solution
A multi-layer plastic film structure with a core layer of polycarbonate or copolycarbonate and/or polyester or copolyester, sandwiched between outer layers of thermoplastic polyurethane and/or polyester or copolyester, which maintains tensile modulus stability under wet or humid conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-layer plastic films are used for three-dimensionally formed articles, then the initial tensile modulus is high, but the tensile modulus drops significantly during use in wet or humid environments
Solution Approach 1:
The patent applies composite materials by creating a multi-layer film structure consisting of at least three layers with different material compositions. The core layer contains polycarbonate/polyester blend, while outer layers contain thermoplastic polyurethane/polyester blend. This composite structure combines the dimensional stability and modulus properties of polycarbonate with the flexibility and moisture resistance of thermoplastic polyurethane, thereby maintaining tensile modulus stability in wet environments without significant property degradation.
Solution Approach 2:
The patent applies segmentation by dividing the single-layer film into multiple functional layers, each with specific thickness ratios and material compositions. The core layer (containing polycarbonate/polyester) is positioned between two outer layers (containing thermoplastic polyurethane/polyester), with specific thickness proportions. This segmentation allows each layer to perform its specialized function: the core layer provides structural stability while outer layers provide moisture resistance and flexibility, collectively solving the tensile modulus drop problem.
2Ease of manufacture
If single-layer films are used in wet environments, then manufacturing is simpler, but the three-dimensional form stability deteriorates during use
Solution Approach 1:
The patent uses composite materials to achieve both manufacturing feasibility and shape stability. The multi-layer structure with specifically selected material combinations (polycarbonate/polyester in core layer, thermoplastic polyurethane/polyester in outer layers) can be produced using conventional co-extrusion techniques, maintaining ease of manufacture while providing superior three-dimensional shape stability in wet environments through the synergistic properties of the composite structure.
Solution Approach 2:
The patent applies local quality by assigning different material properties to different regions (layers) of the film. The core layer uses polycarbonate/polyester for structural rigidity and shape memory, while outer layers use thermoplastic polyurethane/polyester for flexibility and moisture barrier properties. This localized optimization of material properties throughout the film thickness enables the entire structure to maintain three-dimensional shape stability in wet environments while remaining manufacturable.
Data Source
AI summary
The invention relates to a multi-layer, preferably co-extruded, plastic film with improved modulus properties, which is suitable, in particular, for producing three-dimensionally shaped articles.