Biodegradable Polyester Resin with Side-Chain Hydroxyls
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Solution Overview
Problem
Biodegradable polyester resins face limitations in design freedom and biodegradability, especially at higher molecular weights, and existing production methods have high environmental loads.
Innovation Solution
A polyester resin composed of a hydroxy group-containing dicarboxylic acid and a diol component, with over 50 mol% aliphatic diol, achieving a number average molecular weight of 3000 or higher and a total hydroxyl value of 1000 eq/ton or higher, produced through a low-temperature melt polycondensation method at 60 to 150°C, without organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the molecular weight of biodegradable polyester resin is increased, then the mechanical strength and durability are improved, but the hydroxyl value decreases resulting in poor biodegradability
Solution Approach 1:
The patent introduces hydroxyl groups at specific locations (side chains) rather than relying solely on end-group hydroxyls. This local concentration of hydroxyl groups maintains biodegradability even as molecular weight increases, resolving the contradiction between mechanical strength and biodegradability
Solution Approach 2:
The patent pre-introduces hydroxyl-containing dicarboxylic acid components during polymer synthesis to create side-chain hydroxyl groups before the polymerization is complete. This preliminary action ensures that hydroxyl groups are distributed throughout the polymer structure, maintaining biodegradability independent of final molecular weight
2Ease of manufacture
If conventional esterification reaction at 180 to 220°C for 5 to 16 hours is used, then the polyester resin can be produced, but the environmental load increases
Solution Approach 1:
The patent changes the temperature parameter from conventional 180-220°C to a lower range of 60-150°C, and modifies the reaction time to 3-24 hours. This parameter change reduces energy consumption and environmental load while maintaining production feasibility through the use of novel catalyst systems
Solution Approach 2:
The patent replaces the conventional thermal esterification mechanism with an enzyme-catalyzed or metal complex-catalyzed mechanism that operates at lower temperatures. This substitution eliminates the need for high-temperature processing, reducing environmental impact while maintaining ease of manufacture
3Stability of the object's composition
If the hydroxyl value is kept low (0.5 to 5 mg KOH/g), then the resin stability is improved, but the biodegradability becomes insufficient
Solution Approach 1:
The patent creates local concentrations of hydroxyl groups on side chains through the use of hydroxyl-containing dicarboxylic acids, rather than distributing hydroxyl groups uniformly throughout the polymer. This local quality approach allows the resin to maintain overall stability while having specific regions that are susceptible to biodegradation
Solution Approach 2:
The patent creates a composite structure within the polyester molecule, combining stable main chain segments with more labile side-chain segments containing hydroxyl groups. This internal composite structure allows the material to exhibit both resin stability and biodegradability simultaneously
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
The resulting polyester resin exhibits excellent biodegradability and high design freedom, with a degree of biodegradation of 10% or higher within 6 months, while minimizing environmental impact through a low-temperature production process.
Implementation Method 1
the polyester has a degree of biodegradation of 10% or higher within 6 months measured on a basis of a BOD test (aerobic aqueous oxygen consumption measurement) specified in JIS K6950: 2000
Implementation Method 2
A production method for a polyester, the method comprising condensing a hydroxy group-containing dicarboxylic acid and a diol by a low-temperature melt polycondensation method at 60 to 150°C
Data Source
AI summary
An object of the present invention is to provide a polyester resin that has a high degree of freedom in design and that can have excellent biodegradability even with an increased molecular weight. A polyester of the present invention contains a hydroxy group-containing dicarboxylic acid component and a diol component (excluding a hydroxy group-containing dicarboxylic acid component) as copolymerization components, wherein more than 50 mol % of an aliphatic diol component is contained in 100 mol % of the diol component, the polyester has a number average molecular weight of 3000 or higher, and the polyester has a total hydroxyl value of 1000 eq/ton or higher.