Method for Producing Poly-L-Lactic Acid by Directly Polycondensating L-Lactic Acid

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This patent describes a method for producing high-molecular-weight poly-L-lactic acid (PLLA) directly from L-lactic acid through a two-stage process: melt-phase condensation followed by solid-phase condensation. The process uses an acidic, supported solid catalyst—specifically calcined zirconium sulfate supported on mesoporous materials (like silica)—to achieve high purity and high crystallinity PLLA without toxic metal residues. The catalyst can be removed after either stage, resulting in a polymer suitable for demanding applications.

Use CasesContent extracted from patent full text and abstract with AI.

• Biodegradable packaging materials, replacing conventional plastics
• Medical devices such as absorbable sutures and implants
• Pharmaceutical encapsulation for controlled drug release
• Agricultural films and compostable bags
• 3D printing materials requiring high strength and crystallinity
• Textile and fiber production from biodegradable polymers

BenefitsContent extracted from patent full text and abstract with AI.

• Enables the production of high-purity, high-molecular-weight, and highly crystalline PLLA
• Avoids use of toxic tin catalysts, eliminating heavy metal contamination and simplifying purification
• Uses a 'green' catalyst (zirconium sulfate), making the process environmentally friendly
• Facilitates catalyst removal for catalyst-free final products
• Allows tailoring of polymer crystallinity and molecular weight to meet specific end-use requirements
• Employs commercially available starting materials and scalable process steps suitable for industrial implementation

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Patent Abstract

The invention relates to a method for producing high-molecular poly-L lactic acid by directly polycondensating L-lactic acid using a melt-phase condensation and a subsequent solid-phase condensation by means of acidic and supported solid catalysts. The invention also relates to the use of an acidic and supported solid catalyst for producing high-molecular poly-L lactic acid by directly polycondensating L- lactic acid, preferably supported and calcined zirconium sulfate.