PLLA PDLA Nucleating Composition for Hot Beverage Containers
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Solution Overview
Problem
Polylactides are not suitable for manufacturing food containers that need to withstand high temperatures due to their low glass transition temperature and slow crystallization rate, which limits their use in producing thermoformed articles within short cycle times.
Innovation Solution
A thermoformable composition comprising poly-L-lactide with less than 1 mol % of D-lactoyl units, combined with a nucleating combination of poly-D-lactide, talc, and lamellar clay mineral, which enhances crystallization rate and mechanical properties up to 100°C, allowing for the production of biobased and biodegradable containers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polylactide is used for manufacturing food containers, then the containers are biobased and biodegradable, but the material softens at low temperatures (around 50°C) due to low glass transition temperature
Solution Approach 1:
The patent uses a composite material system consisting of PLLA or PLA as the base polymer combined with PDLA as a nucleating agent. This composite approach allows the material to maintain its biodegradable properties while the PDLA component promotes crystallization that raises the effective service temperature and reduces softening, resolving the contradiction between biodegradability and temperature resistance.
2Reliability
If polylactide is used for manufacturing thermoformed articles, then the material is biobased, but the slow crystallization rate prevents sufficient crystallization during short production cycle times
Solution Approach 1:
The patent introduces PDLA as an intermediary substance that acts as a nucleating agent for PLLA or PLA crystallization. The PDLA provides nucleation sites that dramatically accelerate the crystallization rate, enabling sufficient crystallization to occur within short thermoforming cycle times while maintaining the biobased nature of the material system.
3Reliability
If polylactide is used for hot beverage containers, then the containers are environmentally friendly, but they cannot withstand high temperatures (above 50°C) without deformation
Solution Approach 1:
The patent changes the thermal parameters of the polylactide material by incorporating PDLA, which alters the crystallization behavior and raises the temperature at which the material maintains its structural integrity. This parameter change enables the container to withstand hot beverage temperatures while retaining environmental friendliness through biodegradability.
4Reliability
If polylactide is used for single-use food containers, then the containers are biodegradable, but the long crystallization time increases production cycle time and reduces productivity
Solution Approach 1:
The patent employs PDLA as an intermediary nucleating agent that mediates the crystallization process of PLLA or PLA. This intermediary substance provides numerous nucleation sites that drastically reduce the time required for crystallization, allowing single-use containers to be produced rapidly while maintaining their biodegradable 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 solution enables the production of biobased and biodegradable containers with improved mechanical properties and crystallization rates, enabling their use in hot beverage containers without deformation up to 100°C, while also reducing cycle times and improving thermoforming efficiency.
Implementation Method 1
the crystallization rate of these polymers is relatively slow and the polymers exhibit a behavior particularly similar to that of a non-crystalline resin. In view of this relatively long time for crystallization, compositions containing PLA, even homopolymers, do not crystallize sufficiently during the usual short cycle times
Implementation Method 2
b) a nucleating combination consisting of α) 1 to 10% by weight, based on the total amount of the thermoformable resin a), of at least one poly-D-lactide with less than 1 mol % of L-lactoyl-units (PDLA) as component α 1) or of 0.5 to 5% by weight, based on the total amount of the thermoformable resin a), of PLLA/PDLA or PLA/PDLA stereocomplex crystallites
Data Source
AI summary
An essentially biobased and optionally biodegradable, thermoformable composition containinga) as thermoformable resin at least one poly-L-lactide with less than 1 mol % of D-lactoyl units (PLLA) or at least one poly-L-lactide with 1-5 mol % of D-lactoyl units (PLA) andb) a nucleating combination ofα) 1 to 10% Wt. of at least one poly-D-lactide with less than 1 mol % of L-lactoyl-units (PDLA) or of 0.5 to 5% Wt. of PLLA/PDLA or PLA/PDLA stereocomplex crystallites,β) 0.1 to 25% Wt. of an inorganic nucleating agent, andγ) 0.1 to 30% Wt. of at least an inorganic filler with lamellar structure,and thermoformed, essentially biobased and optionally biodegradable containers formed of the inventive compositions.