Polyglycolic Acid Resin Composition for Stable Melt-Formability
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Solution Overview
Problem
The severe hygroscopicity and hydrolyzability of polyglycolic acid resin affect its melt-formability and stability during storage and forming processes, leading to product defects in composite materials like laminate products.
Innovation Solution
A particulate polyglycolic acid resin composition is created by blending two species of polyglycolic acid resins with adjusted moisture contents and melt-viscosities within specific ranges, allowing for stable melt-formability and controlled melt-viscosity through a weighted average calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyglycolic acid resin is dried and stored after polymerization, then it can be processed into various forms, but moisture absorption during storage causes hydrolysis and molecular weight reduction, deteriorating melt-formability
Solution Approach 1:
The patent applies preliminary action by thoroughly drying the polyglycolic acid resin to reduce moisture content to 0.01-5 wt% before storage and processing. This preliminary moisture removal prevents subsequent hydrolysis reactions that would otherwise occur during storage, thereby maintaining molecular weight and melt-formability throughout the storage period and processing stages.
2Ease of operation
If melt-forming temperature is adjusted to control melt-viscosity for polyglycolic acid resin alone, then formability can be optimized, but in composite materials with other thermoplastic resins, the forming conditions cannot be freely changed, resulting in product defects
Solution Approach 1:
The patent applies parameter changes by modifying the molecular weight of the polyglycolic acid resin through controlled hydrolysis to achieve a specific viscosity range (100-10,000 cP at 25°C). This viscosity parameter adjustment allows the resin to be compatible with other thermoplastic resins in composite materials, enabling stable co-extrusion and uniform laminate product formation without requiring frequent forming condition adjustments.
Solution Approach 2:
The patent applies composite materials by creating a blended resin system where polyglycolic acid resin (with controlled molecular weight and viscosity) is combined with other thermoplastic resins. This composite approach ensures that the polyglycolic acid component does not exhibit excessive viscosity changes during processing, allowing stable multi-layer co-extrusion and uniform laminate product formation.
3Adaptability or versatility
If polyglycolic acid resin is used in composite materials through co-extrusion, then diverse product forms can be achieved, but severe hygroscopicity causes molecular weight reduction and melt-viscosity changes, leading to thickness irregularities in laminate products
Solution Approach 1:
The patent applies preliminary action by implementing thorough drying procedures to reduce moisture content to 0.01-5 wt% before the resin is used in composite material formation. This preliminary moisture control prevents hydrolysis-induced molecular weight reduction during storage and processing, ensuring stable melt-viscosity and uniform thickness in laminate products formed through co-extrusion.
Solution Approach 2:
The patent applies parameter changes by controlling the molecular weight of polyglycolic acid resin through regulated hydrolysis to achieve optimal viscosity characteristics (100-10,000 cP at 25°C). This parameter optimization ensures that the resin maintains stable rheological properties during co-extrusion processes, preventing thickness irregularities in composite laminate products.
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 ensures stable formability and processability of polyglycolic acid resin compositions, preventing molecular weight reduction and maintaining desired product properties during storage and forming, even in composite materials.
Implementation Method 1
the resin is liable to cause lowerings of molecular weight and thus melt viscosity directly affecting the melt-formability due to hydrolysis thereof
Data Source
AI summary
A particulate polyglycolic acid resin composition, comprising: a blend of a first particulate polyglycolic acid resin and a second particulate polyglycolic acid resin each having a moisture content of at most 110 ppm and providing a ratio of melt-viscosity (as measured at 270° C. and a shear rate of 121 sec−1; the same as hereinafter) therebetween of above 1 and at most 10. After the polymerization, the first and second particulate polyglycolic acid resins can cause change in properties before the forming (e.g., during storage); or during the forming process. However, by adequately determining the blending ratio between the resins while taking the melt-viscosities thereof into account, it becomes possible to provide a particulate polyglycolic acid resin composition showing a stable melt-formability and suitable as a starting material for various forming processes.