Thermoformed PLA Composite with Heat-Resistant Outer Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polylactic acid (PLA) thermoformed articles lose mechanical strength and deform at temperatures around 140°F (60°C), leading to significant damage during transportation and storage, especially in hot environments, due to its limited heat resistance and deformation resistance.
Innovation Solution
A thermoformable composite is created by coextruding a renewable polymer core with a heat-resistant outer layer, where the renewable polymer comprises at least 60% of the composite and has a Ts value and heat distortion index up to 90°C, while the heat-resistant polymer has a Ts value and heat distortion index greater than 60°C and 50°C respectively, providing enhanced thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PLA is used as the sole polymer material, then the article is renewable and degradable, but the article loses mechanical strength and deforms at temperatures around 140°F (60°C)
Solution Approach 1:
The patent applies composite materials by creating a layered structure consisting of a PLA core layer combined with an outer layer of heat-resistant polymer. This composite structure allows the article to maintain mechanical strength at elevated temperatures while preserving the renewable and degradable properties of the PLA core. The heat-resistant outer layer acts as a protective barrier that prevents deformation even when the PLA core would normally lose strength above 60°C.
Solution Approach 2:
The patent segments the article into distinct functional layers: a core layer made of renewable PLA material and an outer layer made of heat-resistant polymer. This segmentation allows each layer to perform its specific function - the core provides renewable content and the outer layer provides thermal stability - thereby resolving the contradiction between renewability and heat resistance.
2Object-affected harmful factors
If the heat-resistant polymer content is increased to improve temperature resistance, then the deformation resistance improves, but the renewable polymer content decreases
Solution Approach 1:
The patent applies local quality by concentrating the heat-resistant properties in the outer layer while maintaining high renewable polymer content in the core. This localized approach to material properties allows the article to achieve sufficient deformation resistance at the surface (where it contacts hot environments) while preserving the renewable character of the bulk material. The structure ensures that the minimum 40% heat-resistant polymer is positioned where it is most needed for thermal protection.
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 composite exhibits improved resistance to deformation at higher temperatures, effectively protecting against storage and transportation stresses, with the heat-resistant outer layer maintaining structural integrity even when the PLA core loses strength.
Implementation Method 1
a heat-resistant outer layer substantially surrounding the core and comprising a heat-resistant polymer having: (a) a Ts value of greater than about 60° C.; and (b) a heat distortion index of greater than about 50° C.
Implementation Method 2
coextruding the heat-resistant polymer and the renewable polymer to provide the thermoformable composite
Data Source
AI summary
The present invention provides articles comprising a thermoformable composite comprising: a core comprising a renewable polymer having: (a) a Ts value of up to about 90° C.; and (b) a heat distortion index of up to about 90° C.; and a heat-resistant outer layer substantially surrounding the core and comprising a heat-resistant polymer having: (a) a Ts of greater than about 60° C.; and (b) a heat distortion index of greater than about 50° C.; wherein the renewable polymer comprises at least about 60% by weight of the composite, and wherein the heat-resistant polymer has a Ts value and heat distortion index greater than that of the renewable polymer. The present invention also provides methods for coextruding the heat-resistant polymer outer layer and renewable polymer core to provide a thermoformable composite.