Thermoformed Biodegradable Polymer Mixture for Hot Food Containers
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Solution Overview
Problem
Thermoformed items made from existing biodegradable polymer mixtures often lack sufficient heat distortion resistance, stress-strain performance, and biodegradability, particularly for applications in the hot food and drinks sector, and do not meet certification standards for biodegradability.
Innovation Solution
A biodegradable polymer mixture comprising 50-85% of a biodegradable polyester with specific molecular weight and composition, 15-50% polylactic acid, and mineral fillers, optimized for thermoforming to achieve improved mechanical properties, heat distortion resistance, and biodegradability, including the use of succinic acid, 1,3-propanediol or 1,4-butanediol, and a nutrient salt mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing biodegradable polymer mixtures (PBAT+PLA) are used for thermoforming, then biodegradability is achieved, but heat distortion resistance and stress-strain performance are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester component by incorporating specific dicarboxylic acids (adipic, suberic, azelaic, sebacic) in controlled amounts (0.1-10 mol% each) into the PBAT structure. This modification alters the polymer's thermal properties to improve heat distortion resistance while preserving biodegradability through the maintained presence of succinic acid units and overall polyester structure.
Solution Approach 2:
The patent creates a composite polymer system by combining modified polyester (with dicarboxylic acid units) and polylactic acid in a specific weight ratio (70:30 to 30:70). This composite structure synergistically improves both heat distortion resistance and mechanical strength while maintaining biodegradability, as both components are biodegradable polyesters that work together to achieve the required performance.
2Strength
If rigid polymer content is increased to improve mechanical properties, then stress-strain performance improves, but processability and biodegradability rate decrease
Solution Approach 1:
The patent optimizes the weight ratio parameters of the polymer components, specifically setting PLA content between 30-70% by weight. This parameter range provides sufficient rigidity and mechanical strength while maintaining adequate biodegradability rate. The balanced composition ensures that neither component dominates to the extent of compromising the other property.
3Temperature
If polymer mixture composition is optimized for heat resistance, then heat distortion resistance improves, but biodegradability rate decreases
Solution Approach 1:
The patent employs a composite of two biodegradable polyesters (modified PBAT and PLA) where each component contributes different properties. The PBAT phase provides thermal stability and flexibility, while the PLA phase contributes rigidity and also biodegradability. Together in the specified ratio ranges, they achieve heat distortion resistance sufficient for hot food applications while maintaining biodegradability certification capability.
Solution Approach 2:
The patent modifies the polyester structure by incorporating dicarboxylic acids in controlled amounts (0.1-10 mol% of each type), which adjusts the thermal properties to improve heat distortion resistance. However, the modification is limited to preserve the biodegradable nature of the polyester backbone, ensuring that the material can still be certified under biodegradability standards.
4Quantity of substance
If wall thickness is reduced for thin-walled applications, then material usage decreases, but heat distortion resistance and structural integrity worsen
Solution Approach 1:
The patent changes the compositional parameters of the polymer mixture to create a material with enhanced intrinsic heat resistance and mechanical strength. By optimizing the ratio of modified polyester to PLA (70:30 to 30:70) and incorporating dicarboxylic acids into the polyester structure, the material achieves sufficient performance even at reduced wall thicknesses, enabling thin-walled designs that maintain structural integrity under thermal and mechanical loads.
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 polymer mixture exhibits enhanced mechanical properties, heat distortion resistance, and biodegradation performance, meeting ISO and EN biodegradability standards, and is suitable for applications with varying wall thicknesses.
Implementation Method 1
biodegradability rate should moreover be sufficiently high for certification to ISO 17088 and/or EN 13432 and/or ASTM D6400
Implementation Method 2
a biodegradable polymer mixture comprising 50-85% of a biodegradable polyester with specific molecular weight and composition
Data Source
AI summary
The present invention relates to an item produced via thermoforming and comprising:i) a biodegradable polyester comprising:a) succinic acid;b) optionally one or more C6-C20 dicarboxylic acids;e) 1,3-propanediol or 1,4-butanediol;f) a chain extender or branching agent;ii) polylactic acid;iii) at least one mineral filler;The invention further relates to processes for producing the abovementioned items.