Biodegradable Copolyester Hot Melt Adhesive via Depolymerized PET
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Solution Overview
Problem
Conventional hot melt adhesives used in plastic packaging materials, such as straw glue and bottle labeling, are non-biodegradable and cannot be recycled, leading to environmental pollution and carbon footprint issues due to residual adhesives.
Innovation Solution
A biodegradable copolyester is developed by copolymerizing depolymerized polyester with succinic acid, using an antimony-based catalyst to achieve a suitable storage modulus for use as a hot melt adhesive, ensuring thermal stability and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional hot melt adhesive is used in plastic packaging, then adhesion performance is achieved, but biodegradability is lost and environmental pollution increases
Solution Approach 1:
The patent creates a composite material system by copolymerizing depolymerized PET with succinic acid to form a copolyester that combines the adhesion properties needed for hot melt adhesive with biodegradability. The copolymer structure integrates different functional units that provide both bonding capability and environmental compatibility.
Solution Approach 2:
The patent modifies the chemical composition parameters by controlling the molar ratio of repeating units from PET (40-50%) to succinic acid (50-60%), and adjusting the ethylene glycol ratio (50-100%), to achieve the optimal balance between storage modulus, adhesion performance, and biodegradability in the hot melt adhesive application.
2Object-affected harmful factors
If biodegradable materials are used for hot melt adhesive, then environmental compatibility is improved, but storage modulus and thermal stability deteriorate
Solution Approach 1:
The patent precisely controls the compositional parameters of the copolyester, maintaining repeating units from PET at 40-50% and succinic acid at 50-60%, with ethylene glycol at 50-100% molar ratio. This parameter optimization ensures the copolyester achieves sufficient storage modulus (1×10^4 to 1×10^6 Pa at 80°C) while preserving biodegradability.
Solution Approach 2:
The copolyester functions as a composite material system where depolymerized PET provides structural integrity and thermal stability, while succinic acid contributes biodegradability. The synergistic combination of these components delivers both mechanical strength and environmental compatibility required for hot melt adhesive applications.
3Ease of manufacture
If PET is depolymerized with ethylene glycol, then recyclability is achieved, but molecular weight control becomes challenging
Solution Approach 1:
The patent controls the depolymerization process by optimizing the molar ratio of ethylene glycol to PET repeating units (50-100%), which regulates the extent of depolymerization and resulting molecular weight distribution. This parameter control enables consistent production of copolyester with suitable viscosity and molecular characteristics for hot melt adhesive processing.
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 copolyester exhibits excellent biodegradability, viscosity, and thermal stability, making it suitable for use in hot melt adhesives, addressing the limitations of conventional biodegradable materials in this application.
Implementation Method 1
a copolyester formed by copolymerizing a depolymerized polyester and succinic acid
Implementation Method 2
The depolymerized PET is formed by depolymerizing PET with ethylene glycol
Implementation Method 3
The copolyester has a storage modulus of 1*104 Pa to 1*106 Pa at 80° C.
Data Source
AI summary
A copolyester is formed by copolymerizing a depolymerized polyester and succinic acid. The depolymerized polyester includes depolymerized polyethylene terephthalate (PET), and the depolymerized PET is formed by depolymerizing PET with ethylene glycol. The repeating unit of PET and the succinic acid have a molar ratio of 40:60 to 50:50. The repeating unit of PET and the ethylene glycol have a molar ratio of 100:100 to 100:500. The copolyester has a storage modulus of 1*104 Pa to 1*106 Pa at 80° C. The copolyester can be used in a hot melt adhesive.