Lactide Synthesis Device with Vacuum Depolymerization
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Solution Overview
Problem
Current methods for synthesizing lactide are inefficient, resulting in long residence times and high costs due to low yields, which hampers industrial production.
Innovation Solution
A method involving polymerization synthesis of oligolactic acid from L-lactic acid, D-lactic acid, or DL-lactic acid at controlled temperatures and pressures, followed by purification and depolymerization using catalysts to produce lactide with high yield and molecular weight, utilizing a device comprising oligomer preparation, purification, depolymerization, and purification systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional depolymerization methods are used, then lactide can be produced, but the residence time is long (40 minutes to 4 hours) and efficiency is low
Solution Approach 1:
The patent changes the physical state parameters by conducting depolymerization under vacuum conditions (0.1-10 kPa) rather than atmospheric pressure, and uses specific temperature ranges (200-260°C) to optimize the reaction kinetics. This parameter optimization reduces residence time from hours to minutes while maintaining high lactide yield
Solution Approach 2:
The patent introduces zinc-based catalysts (zinc oxide, zinc lactate, zinc acetate) as intermediaries to facilitate the depolymerization reaction. These catalysts lower the activation energy and accelerate the conversion of oligolactic acid to lactide, dramatically reducing residence time and improving production efficiency
2Manufacturing precision
If direct polycondensation of lactic acid is performed, then polylactic acid can be obtained, but the molecular weight is low and application value is reduced
Solution Approach 1:
The patent divides the synthesis process into two distinct stages: first forming oligolactic acid intermediates with controlled molecular weight (500-3000 Da), then depolymerizing to lactide monomers for ring-opening polymerization. This segmentation allows precise control over final polylactic acid molecular weight and eliminates the limitation of direct polycondensation
Solution Approach 2:
The patent performs preliminary purification of oligolactic acid to remove unreacted lactic acid and water before depolymerization. This preliminary action ensures high purity lactide production and prevents side reactions that would limit molecular weight in direct polycondensation methods
3Ease of manufacture
If conventional synthesis methods are used, then lactide can be produced, but the cost is high due to low yield and long processing time
Solution Approach 1:
The patent implements continuous vacuum depolymerization where the reaction proceeds continuously under vacuum conditions, maintaining optimal temperature and pressure throughout the process. This continuous action achieves 94-98% lactide yield within minutes, dramatically reducing both time and cost compared to batch methods
Solution Approach 2:
The patent replaces conventional thermal depolymerization with catalyst-mediated depolymerization under vacuum. The zinc-based catalysts substitute for prolonged thermal processing, reducing energy consumption and processing time while achieving superior yield and cost-effectiveness
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 method significantly reduces lactide synthesis time and increases yield, achieving a lactide product with 94% to 98% purity and allowing for efficient industrial production.
Implementation Method 1
carrying out a polymerization synthesis reaction at 100° C. to 180° C. under an absolute pressure of of 1 KPa to 100 KPa... to obtain oligolactic acid with a weight-average molecular weight of 500 Da to 3,000 Da
Implementation Method 2
depolymerizing the oligolactic acid purified in step (2) under an action of a catalyst at 200° C. to 260° C. under an absolute pressure of 0.1 KPa to 1 KPa... to obtain a lactide product
Implementation Method 3
purifying the oligolactic acid obtained in step (1) to remove unreacted lactic acid and water... under an absolute pressure of 0.1 KPa to 1 KPa
Implementation Method 4
purifying and collecting the light component to obtain a lactide product, and refluxing and depolymerizing the heavy component again
Data Source
AI summary
The invention discloses a synthesis method and device for rapidly producing lactide at high yield. The method comprises: adding a single component of lactic acid or two components of lactic acid and catalyst, passing the mixture through a mixer to enter an oligomer preparation system, increasing a residence time through bottom circulation, synthesizing oligomeric lactic acid, and passing a gas-phase component through a rectification system. With the adoption of the device, the lactide is capable of being efficiently synthesized, crude lactide with a yield of 94% to 98% is capable of being obtained.