Lactide Purification via Thermal Oligomerization
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Solution Overview
Problem
The existing methods for manufacturing lactide through depolymerization of lactic acid oligomers face challenges in efficiently separating volatile components, particularly lactic acid, and coloring substances during the distillation process, which can negatively impact polymerization processes and result in impurities.
Innovation Solution
The method involves maintaining crude lactide in a reaction vessel at a temperature between 97°C and 200°C for a period of at least 5 hours, allowing for the conversion of lactic acid into lactic acid oligomers, which can be more easily separated during distillation, thereby reducing lactic acid content by over 20% and improving the overall efficiency of the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If crude lactide is directly distilled after depolymerization, then the distillation process can proceed quickly, but the separation of volatile components like lactic acid and coloring substances becomes cumbersome and inefficient
Solution Approach 1:
The patent applies preliminary action by maintaining crude lactide at 97-200°C for at least 5 hours before distillation. This pre-treatment step converts lactic acid into lactic acid oligomers and removes coloring substances through thermal degradation, making the subsequent distillation process much more efficient at separating volatile impurities.
Solution Approach 2:
The patent changes the temperature parameter by maintaining crude lactide at elevated temperatures (97-200°C) for an extended period before distillation. This parameter change facilitates the conversion of lactic acid to oligomers and degradation of coloring substances, fundamentally altering the composition to improve separability during distillation.
2Loss of time
If distillation is performed without pre-treatment, then the process time is shorter, but the lactic acid content in the purified lactide remains high and negatively impacts polymerization
Solution Approach 1:
The patent performs preliminary thermal treatment at 97-200°C for at least 5 hours to convert lactic acid into lactic acid oligomers before distillation. This preliminary action reduces lactic acid content by over 20%, ensuring the purified lactide has sufficient quality for polymerization while maintaining reasonable overall process time.
3Manufacturing precision
If crude lactide is maintained at high temperature for extended periods, then lactic acid converts to oligomers improving purity, but energy consumption increases
Solution Approach 1:
The patent optimizes the temperature parameter range (97-200°C) and time parameter (at least 5 hours) to achieve effective lactic acid conversion to oligomers. This parameter optimization balances energy consumption with purification efficiency, ensuring sufficient lactic acid removal while avoiding excessive energy waste.
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 enhances the purity of lactide by reducing lactic acid content and improving the separation of impurities, leading to a more efficient lactide production process with higher purity and reduced acidity, making it suitable for polymerization.
Implementation Method 1
maintaining crude lactide in a reaction vessel at a temperature between 97°C and 200°C for a period of at least 5 hours, allowing for the conversion of lactic acid into lactic acid oligomers
Implementation Method 2
crude lactide is purified from impurities like water, lactic acid, lactoyl lactate and other possible condensation reaction byproducts
Data Source
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AI summary
The invention relates to a method and a device for manufacturing lactide, whereby crude lactide, being prepared by means of depolymerization of lactic acid oligomers, is purified by means of a distillation step. According to the invention, the prepared crude lactide is maintained for a period of at least 5 hours in a reaction vessel at a temperature between 97º C and 200º C prior to the distillation step. Keeping the lactide during a period of time in a reaction vessel leads to a decrease of the lactic acid content and an increase of the lactic acid oligomer concentration, so that the resulting crude lactide can be more efficiently purified during subsequent distillation. A pre-distilling step gives additional advantages.