Multilayer Polyester Container Structure for Bleach Resistance and Recycling
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Solution Overview
Problem
Existing polyester resin containers for chlorine-based bleaching agents suffer from mechanical deterioration, cracking, and delamination, and recycled polyester resin often experiences yellowing, necessitating improved resistance and yellowing suppression.
Innovation Solution
A multilayer hollow container design featuring a polyester layer and an intermediate polyamide layer containing a yellowing inhibitor, with the polyamide layer extending from the ground contact portion to 10-70% of the container height, using specific polyamide and polyester resin compositions and controlled amounts of yellowing and greening inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyester resin is used as the main base material for containers containing chlorine-based bleaching agents, then the container can be manufactured with good appearance and mechanical performance, but the mechanical properties deteriorate during long-term storage due to hydrolysis of the ester bond
Solution Approach 1:
The invention uses a multilayer composite structure consisting of a polyester resin layer and a polyamide resin layer. The polyester layer provides good appearance and mechanical performance, while the polyamide layer provides resistance to chlorine-based bleaching agents and prevents hydrolysis, thereby maintaining mechanical property stability during long-term storage.
2Object-affected harmful factors
If polyamide resin is added to polyester resin composition to improve gas barrier properties, then gas barrier properties are enhanced, but yellowing due to heat history occurs more readily during recycling
Solution Approach 1:
The invention places the polyamide resin layer specifically at the bottom portion of the container (from the ground contact portion to a position of 10 to 70% of the height). This localized placement provides gas barrier properties where needed while minimizing the overall amount of polyamide resin, thereby reducing yellowing during recycling.
3Strength
If a multilayer container structure is adopted to improve delamination resistance and cracking resistance, then structural integrity is enhanced, but the container becomes more complex to manufacture
Solution Approach 1:
The invention divides the container into multiple layers with distinct functions: a polyester resin layer for appearance and basic mechanical performance, and a polyamide resin layer for chemical resistance and gas barrier properties. This segmentation allows each layer to optimize its specific function while maintaining overall structural integrity and resistance to delamination and cracking.
4Adaptability or versatility
If polyester resin is used for containers, then recyclability is improved, but yellowing occurs during the recycling process reducing product value
Solution Approach 1:
The invention minimizes the amount of polyamide resin by placing it only in the bottom portion of the container (10 to 70% of the height from the ground contact portion). This reduces the overall polyamide content in the recyclable material, thereby minimizing yellowing during recycling while maintaining necessary functional properties.
Data Source
AI summary
Provided is a multilayer hollow container including: a polyester layer containing a polyester resin (X); and a polyamide layer containing a polyamide resin (Y) and a yellowing inhibitor (A) with the polyamide layer being an intermediate layer and being present from a ground contact portion to a position of from 10 to 70% of a height of the multilayer hollow container. Also provided are a method for manufacturing the multilayer hollow container, and a method for manufacturing a recycled polyester, the method thereof including a step of recovering polyester from the multilayer hollow container.