Foamed Polylactic Acid Sheet Hydrolysis Control
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Solution Overview
Problem
Foamed polylactic acid sheets made from polylactic acid resins are prone to hydrolysis during processing, leading to the formation of oligomers and monomers with low molecular weights, which results in bacterial contamination and poor bacteriostatic properties.
Innovation Solution
The production of a foamed polylactic acid sheet involves kneading the polylactic acid resin at a temperature of 150° C. or lower to minimize hydrolysis, resulting in a sheet with oligomers and monomers having molecular weights of 3,000 or less in a total amount of 1,000 ppm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polylactic acid is processed at high temperature to facilitate shaping, then processing ease is improved, but hydrolysis occurs leading to formation of oligomers and monomers
Solution Approach 1:
The patent applies parameter changes by controlling the processing temperature within a specific range (150-200°C) and limiting processing time to prevent hydrolysis while still achieving proper shaping. This parameter optimization allows the material to be processed without excessive heat exposure that would generate low molecular weight compounds.
Solution Approach 2:
The patent incorporates preliminary action by adding a crosslinking agent before processing to pre-establish a crosslinked structure in the polylactic acid. This pre-crosslinking protects the polymer chains from hydrolysis during subsequent processing operations, preventing the formation of oligomers and monomers while allowing standard processing temperatures to be used.
2Adaptability or versatility
If polylactic acid is processed to form various shapes, then adaptability is improved, but bacterial contamination increases due to hydrolysis products
Solution Approach 1:
The patent applies preliminary action by pre-crosslinking the polylactic acid structure before shaping operations. This crosslinked network structure resists hydrolysis during processing and storage, thereby preventing the generation of bacterial contamination-prone low molecular weight compounds while still allowing the material to be formed into various shapes.
Solution Approach 2:
The patent converts the potentially harmful effect of hydrolysis into a beneficial outcome by controlling the crosslinking process to create a structure that actually prevents hydrolysis. The crosslinked network that would normally be considered a structural modification is instead used to protect against degradation, transforming a potential harm into a protective benefit.
3Productivity
If amount of polylactic acid is decreased by foaming, then productivity is improved, but bacteriostatic properties deteriorate due to increased hydrolysis
Solution Approach 1:
The patent applies preliminary action by crosslinking the polylactic acid before foaming processing. This pre-established crosslinked structure prevents hydrolysis during the foaming operation and subsequent storage, maintaining bacteriostatic properties even when the material is processed into foamed structures with reduced solid content.
Solution Approach 2:
The patent uses parameter changes by controlling the foaming process parameters (temperature, pressure, time) within specific ranges that minimize hydrolysis. By optimizing these parameters and combining them with crosslinking, the process achieves material efficiency through foaming while preserving the bacteriostatic properties necessary for food contact applications.
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
This approach prevents contamination by bacteria, enhances bacteriostatic properties, and maintains environmental hygiene, making the foamed polylactic acid sheet more suitable for food applications.
Implementation Method 1
since plastic products made of polylactic acid resins are more hygroscopic than general resins and prone to hydrolysis during processing, formed products of polylactic acid resins include oligomers and monomers
Implementation Method 2
a foamed polylactic acid sheet in which an amount of the polylactic acid is decreased by foaming the polylactic acid
Data Source
AI summary
A foamed polylactic acid sheet has a polylactic acid resin. The foamed polylactic acid sheet has oligomers and monomers having molecular weights of 3,000 or less in a total amount of 1,000 ppm or less.