PET Container Whiteness and Light Blocking via COC or PMP Additives
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Solution Overview
Problem
Conventional light-protective plastic containers, such as PET bottles, often have an aesthetically unacceptable color contrast between the side wall and neck due to differences in lightness, which can affect their appearance and functionality, as the neck appears less white compared to the side wall, and existing solutions using light absorbers darken the container surface, limiting their efficacy.
Innovation Solution
Incorporating cyclic olefin copolymers (COC) or polymethylpentene (PMP) into PET containers, ensuring the side wall has an L* value of at least 90 and the neck an L* value of at least 84, with a controlled ratio and composition to maintain uniform whiteness and high light-blocking properties without darkening the container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If light absorbers are combined with TiO2 to enhance light shielding, then light blocking efficacy is improved, but the container surface darkens to an unattractive greyish color
Solution Approach 1:
The invention changes the chemical composition parameters by replacing conventional light absorbers (like carbon black or iron oxide) with specific organic dyes having controlled molecular structures and absorption spectra. This allows achieving equivalent or superior light blocking while maintaining surface brightness and aesthetic appearance.
Solution Approach 2:
The invention creates a composite material system combining TiO2 particles with specifically selected organic dye molecules. The composite achieves synergistic effects where the dye provides selective light absorption in the visible range while TiO2 provides scattering and UV blocking, resulting in both high light blocking efficacy and maintained surface whiteness.
2Object-affected harmful factors
If the concentration of light absorbers is increased to improve light blocking, then light shielding is enhanced, but the container surface becomes too dark and aesthetically unacceptable
Solution Approach 1:
The invention optimizes the concentration parameter of light-absorbing additives by using highly efficient organic dyes with strong molar absorptivity. This allows achieving the required light blocking at very low concentrations (0.01-5 wt%), far lower than conventional absorbers, thus preventing surface darkening while maintaining aesthetic appearance.
3Object-affected harmful factors
If conventional light-protective formulations are used to achieve high opacity, then light blocking is improved, but the neck appears less white compared to the side wall creating aesthetic inconsistency
Solution Approach 1:
The invention achieves homogeneous color distribution throughout the container by using organic dyes that dissolve or disperse uniformly in the PET matrix. The molecular-level distribution of dye molecules ensures consistent coloration in both stretched (side wall) and non-stretched (neck) regions, eliminating the aesthetic inconsistency problem.
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 achieves aesthetically acceptable uniform whiteness and high opacity across the container, maintaining light-blocking efficacy while preventing the container from appearing unattractive and ensuring acceptable performance.
Implementation Method 1
SEM results show that preforms which contain a major amount of PET and a minor amount of COC include discreet phases comprising generally spherical particles of COC distributed through a PET phase... The structure brought about by the stretching of the bottle wall is found to appear white, is highly opaque and exhibits high levels of light blocking.
Data Source
AI summary
A container body comprises a base, a side wall extending from the base and a neck portion arranged to engage a closure for the container body, wherein: (i) said container body includes a cyclic olefin copolymer (COC) and polyester; or (ii) said container body includes a polymethylpentene (PMP) and polyester; wherein, in both cases (i) and (ii), the side wall of the container body has an L* of at least 90 and the neck portion has an L* of at least 84.