Biodegradable Resin Composition Balancing Composting Speed and Film Strength
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Solution Overview
Problem
Existing biodegradable plastics, such as polylactic acid, have slow degradation rates under home composting and soil burial conditions, and other polymers like polyhydroxyalkanoate and polyglycolic acid lack desirable processing stability, viscoelasticity, thermal properties, and barrier properties for film applications.
Innovation Solution
A biodegradable resin composition with an intrinsic viscosity of 1.0 dL/g or more, containing 70 wt% polylactic acid, specific carboxyl groups, and additives like aliphatic polyesters and polycarbonates, ensuring rapid biodegradation and maintaining mechanical and thermal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polylactic acid is used as biodegradable plastic, then processing performance and mechanical properties are improved, but biodegradation speed becomes very slow under home composting and soil burial conditions
Solution Approach 1:
The patent uses a composite resin composition containing polylactic acid (30-80 wt%), polyhydroxyalkanoate (5-50 wt%), and optionally poly(butylene adipate-co-terephthalate) or poly(butylene succinate) (5-50 wt%). This composite structure combines the fast biodegradation capability of polyhydroxyalkanoate with the excellent processing and mechanical properties of polylactic acid, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent controls the intrinsic viscosity of the resin composition within a specific range (0.03-0.15 dL/g) and adjusts the molecular weight distribution and composition ratios to optimize both biodegradation speed and processing performance. By precisely controlling these parameters, the patent achieves rapid biodegradation while maintaining good mechanical properties.
2Productivity
If polymers like polyhydroxyalkanoate and polyglycolic acid are used to achieve fast biodegradation, then biodegradation speed is improved, but processing stability, viscoelasticity, thermal properties, and barrier properties deteriorate
Solution Approach 1:
The patent creates a composite material system where polyhydroxyalkanoate (providing fast biodegradation) is combined with polylactic acid (providing excellent processing and mechanical properties) and optionally with poly(butylene adipate-co-terephthalate) or poly(butylene succinate). This composite approach allows each component to contribute its advantageous properties to the final material.
Solution Approach 2:
The patent assigns different functional roles to different components: polyhydroxyalkanoate provides fast biodegradation capability, polylactic acid provides processing stability and mechanical strength, and the optional butylene succinate/PBAT components enhance flexibility and processability. This local specialization of functions resolves the contradiction between biodegradation speed and overall material performance.
3Strength
If intrinsic viscosity is increased to improve mechanical properties, then strength and stability are improved, but biodegradation speed decreases
Solution Approach 1:
The patent optimizes the intrinsic viscosity parameter to a specific range (0.03-0.15 dL/g) rather than maximizing it. This optimized parameter range allows the resin to maintain sufficient mechanical strength and stability while preserving rapid biodegradation capability. The patent demonstrates that higher intrinsic viscosity (e.g., >0.15 dL/g) results in slower biodegradation rates.
Solution Approach 2:
The composite resin composition allows the system to achieve high mechanical strength through the combination of components with different properties, rather than relying solely on high intrinsic viscosity. The polyhydroxyalkanoate provides fast biodegradation even when the overall intrinsic viscosity is optimized for strength, resolving the contradiction between these two 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 resin achieves rapid biodegradation within 6 months, with a loss rate of intrinsic viscosity suitable for stable storage and excellent film properties, including high tensile strength and barrier properties.
Implementation Method 1
the biodegradation mechanism mainly involves the hydrolysis of ester bonds in the polymer chain
Implementation Method 2
heat treatment at elevated temperatures for a certain period of time, thereby accelerating the biodegradation process
Data Source
AI summary
The present invention provides a biodegradable resin having an intrinsic viscosity of 1.0 dL/g or more, and having a loss rate of intrinsic viscosity of 10% or more after treatment at 70° C. and 85% RH for 6 hr. The present invention also provides a biodegradable resin containing 70 wt % or more of polylactic acid and having a relative biodegradation rate up to 90% or more within 12 months when the degradability in home composting at 28° C. is evaluated according to the conditions specified in ASTM D5338-15. The biodegradable resin has the characteristics of fast biodegradation speed and stable storage, has good mechanical properties, optical properties and barrier properties, can be applicable to various aspects including packaging and express transportation, and will quickly biodegrade into carbon dioxide, water and other small molecules without contamination to the environment at the end of service life. The present invention also provides a biodegradable resin film using the biodegradable resin and a product thereof, and a multilayer film containing the biodegradable resin film and a product thereof.