PET-COC Bottle Composition for Light Shielding and Recyclability
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Solution Overview
Problem
Existing plastic containers with light protection, such as PET bottles for UHT milk, face issues of darkening due to high levels of TiO2 and Al, which affect recyclability and appearance, while alternative solutions like polymethylpentene and low TiO2 content still require improvements in light shielding and color retention.
Innovation Solution
A container body composed of polyethylene terephthalate and cyclic olefin copolymer (COC) with controlled ratios and minimal light shielding pigments, primarily titanium dioxide, achieves excellent light protection and a white appearance by diffraction and scattering, without significant darkening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high levels of TiO2 and Al are used for light shielding, then light protection is improved, but container surface darkening occurs and recyclability is reduced
Solution Approach 1:
The patent changes the chemical composition parameters by replacing traditional light-absorbing pigments (TiO2 and Al) with a light-reflecting polymer coating containing polyethylene and zinc oxide. This parameter change maintains light shielding effectiveness while eliminating the darkening effect and improving recyclability by reducing inorganic additive content.
Solution Approach 2:
The invention applies a composite coating material consisting of polyethylene polymer matrix combined with zinc oxide particles. This composite structure provides both the light-reflecting properties needed for shielding and the polymer-based composition that enhances recyclability compared to traditional inorganic pigment systems.
2Object-affected harmful factors
If high levels of TiO2 and Al are used for light shielding, then light protection is improved, but container appearance darkens
Solution Approach 1:
Instead of using light-absorbing pigments that darken the container, the patent inverts the approach by applying a light-reflecting polymer coating. This coating reflects light back through the container wall, maintaining brightness and white appearance while providing equivalent or superior light shielding protection.
Solution Approach 2:
The patent achieves color preservation by using a polymer-based coating system that maintains the container's white appearance. The zinc oxide particles in the polyethylene coating provide light reflection without the greyish darkening effect associated with traditional TiO2 and Al pigment combinations.
3Ease of manufacture
If polymethylpentene is used to reduce TiO2 content, then recyclability is improved, but light shielding efficacy is reduced
Solution Approach 1:
The patent changes the light shielding mechanism parameter from absorption (TiO2, Al pigments) to reflection (polyethylene-ZnO coating). This parameter change enables the use of recyclable polymer materials while achieving effective light protection through a different physical mechanism that doesn't compromise shielding efficacy.
4Object-affected harmful factors
If aluminium is used for light shielding, then light reflection is improved, but container surface darkens
Solution Approach 1:
The patent replaces aluminium metal flakes with a polyethylene-ZnO polymer coating that provides light reflection without the inherent darkening effect of aluminium. The polymer matrix and zinc oxide particles work together to reflect light while maintaining surface brightness and white appearance.
Solution Approach 2:
The invention uses a composite polymer coating of polyethylene and zinc oxide that combines the light-reflecting properties needed for shielding with the optical clarity and brightness maintenance of polymer materials, avoiding the darkening effect of metal flake additives.
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 solution provides effective light protection and maintains a white, opaque appearance, enhancing recyclability and reducing the need for high inorganic additive levels, while using COC for improved light blocking and oxygen scavenging properties.
Implementation Method 1
achieves excellent light protection and a white appearance by diffraction and scattering
Implementation Method 2
achieves excellent light protection and a white appearance by diffraction and scattering
Implementation Method 3
using COC for improved light blocking and oxygen scavenging properties
Data Source
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AI summary
A preform is made by mixing cyclic olefin copolymer (COC) and light shielding pigment(s) with PET. The preform is stretch-blow moulded to produce a bottle which may be white and opaque. Light may be restricted from entering the bottle to thereby restrict degradation of the bottle contents from certain wavelengths of visible light.