Multilayer Container Yellowing Suppression via Polyamide Inhibitor
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Solution Overview
Problem
Existing multilayer containers face challenges in suppressing yellowing and hue changes during the recycling of polyester resins, particularly when containing polyamide layers, which affects the product's value and requires significant resources and costs for manufacturing.
Innovation Solution
A multilayer container design with specific compositions, including a polyester layer and a polyamide layer containing a polyamide resin and a yellowing inhibitor, where the polyamide resin content is between 0.05 to 7.0 mass% and the yellowing inhibitor is present at 1 to 30 ppm, to minimize hue changes and improve recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyamide resin layer is added to improve gas barrier properties, then gas barrier performance is improved, but yellowing occurs during recycling
Solution Approach 1:
A polyester resin layer is introduced as an intermediary between the polyamide resin layer and the external environment. This polyester layer acts as a protective barrier that prevents direct contact between oxygen/light and the polyamide, thereby suppressing yellowing while maintaining the gas barrier properties provided by the polyamide layer.
Solution Approach 2:
The invention uses a composite multilayer structure combining polyester resin and polyamide resin layers. This composite structure leverages the complementary strengths of each material: polyester provides resistance to yellowing and good processability, while polyamide provides superior gas barrier properties, achieving both goals simultaneously.
2Object-affected harmful factors
If a yellowing inhibitor is added to suppress yellowing, then yellowing is suppressed, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using expensive and complex yellowing inhibitors that require precise dosing and specialized handling, the invention employs a simple polyester resin layer that naturally resists yellowing. This approach uses a readily available, inexpensive material that eliminates the need for additional chemical additives and complex manufacturing processes.
Solution Approach 2:
The polyester resin layer inherently possesses resistance to yellowing without requiring any additional yellowing inhibitor additives. The material structure itself provides the yellowing suppression function, eliminating the need for external chemical agents and simplifying the manufacturing process.
3Object-affected harmful factors
If a large amount of yellowing inhibitor is used to suppress yellowing, then yellowing suppression is improved, but moldability and cost deteriorate
Solution Approach 1:
The invention replaces the need for large amounts of yellowing inhibitor chemicals with a simple polyester resin layer structure. This approach uses inexpensive base materials that do not require precise dosing, avoiding the moldability issues and cost increases associated with high concentrations of inhibitor additives.
Solution Approach 2:
Instead of changing the chemical composition by adding large amounts of yellowing inhibitors, the invention changes the structural parameter by introducing a polyester resin layer. This structural modification achieves yellowing suppression without altering the chemical parameters that would affect moldability and increase cost.
Data Source
AI summary
Provided is a multilayer container including: a polyester layer containing a polyester resin (X); and a polyamide layer containing a polyamide resin (Y) and a yellowing inhibitor (A). The content of the polyamide resin (Y) is from 0.05 to 7.0 mass% relative to a total amount of all polyamide layers and all polyester layers, and the content of the yellowing inhibitor (A) is from 1 to 30 ppm relative to the total amount of all polyamide layers and all polyester layers. Also provided are a method for manufacturing the multilayer container, and a method for manufacturing a recycled polyester, the method thereof including a step of recovering polyester from the multilayer container.