Opaque Polyester Containers with Segmented Barrier Layers
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Solution Overview
Problem
Current stretch-blow-molded polyester containers are transparent, limiting the selection of barrier materials and oxygen scavengers due to the need to maintain clarity, which restricts cost-effective production processes and allows for haziness or color issues.
Innovation Solution
Development of opaque stretch-blow-molded polyester containers with less than 15% visible light transmission, using compatible opacifying materials like metal powders, metal oxides, and nanoparticles, allowing for a broader range of barrier and scavenging materials without worrying about haziness or color, and enabling easier recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transparent polyester containers are used to allow consumers to see food items, then consumer preference is satisfied, but the selection of barrier materials and oxygen scavengers is limited due to haziness and discoloration concerns
Solution Approach 1:
The patent divides the container into two functional layers: an inner opaque layer containing opacifying particles (titanium dioxide, aluminum powder, or calcium carbonate) that blocks light and masks discoloration, and an outer layer that can be transparent or translucent. This segmentation allows the inner layer to provide barrier functionality with scavengers and dyes while the outer layer maintains consumer visibility of contents.
Solution Approach 2:
The patent applies different optical properties to different parts of the container structure. The inner layer is made opaque with high light-blocking capability to conceal additives and prevent light transmission, while the outer layer is kept transparent or translucent to allow consumers to see the food items inside, thus satisfying both functionality and consumer preference.
2Illumination intensity
If opacifying materials are added to polyester resin to block visible light, then light transmission is reduced to less than 15%, but the container becomes opaque and cannot display food items
Solution Approach 1:
The patent segments the container into an inner opaque layer for light blocking and an outer transparent layer for visibility. The inner layer contains opacifying particles at concentrations providing greater than 90% light blockage, while the outer layer maintains transparency, thus resolving the contradiction between light blocking and food visibility.
Solution Approach 2:
The patent creates a composite structure combining opaque and transparent materials in a multi-layer configuration. The inner layer uses polyester resin with opacifying particles (titanium dioxide, aluminum powder, or calcium carbonate) to block light, while the outer layer uses clear polyester to allow visibility, achieving both light blocking and food display functions simultaneously.
3Reliability
If barrier materials and scavenger compounds are used to improve gas permeation properties, then oxygen and carbon dioxide barrier is enhanced, but the container may develop haziness or discoloration
Solution Approach 1:
The patent segments the container into an inner opaque layer that houses all barrier materials and scavenger compounds, isolating their potential discoloration effects from the outer transparent layer. This segmentation allows high concentrations of scavengers and dyes to be used in the inner layer without compromising the clarity of the outer layer, thus improving gas barrier properties while maintaining consumer visibility.
Solution Approach 2:
The patent converts the potential harm of discoloration and haziness caused by barrier materials and scavengers into a benefit by using the opaque inner layer to mask these effects. The opacifying particles transform the aesthetic disadvantage of additive-induced discoloration into a functional advantage, allowing higher concentrations of barrier materials to be used without visual penalty.
4Illumination intensity
If clear, colorless resin is used to maintain transparency, then consumer preference for visible food is satisfied, but the use of certain additives is restricted
Solution Approach 1:
The patent segments the resin system into an inner opaque layer where additives can be freely used without aesthetic concern, and an outer transparent layer that maintains consumer visibility. This segmentation removes the restriction on additive selection while preserving the transparency benefit, as the opaque inner layer acts as a shield against discoloration.
Solution Approach 2:
The opaque inner layer acts as an intermediary between the additives (barrier materials and scavengers) and the outer transparent layer. It mediates the interaction by absorbing and masking the discoloration effects of additives, allowing clear resin to be used in the outer layer without restricting additive selection in the inner layer.
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 opaque containers provide improved gas barrier and oxygen scavenging properties, reduce sticking issues, and allow for the use of previously restricted additives, enhancing production efficiency and product appearance while maintaining recyclability.
Implementation Method 1
Opaque polyester containers having less than 15% transmission of visible light (500 nm) through a 0.4-millimeter wall
Implementation Method 2
The opacifying material may be any material compatible with polyester resin. Generally, the finer the powder, the better the opacifying properties.
Data Source
AI summary
The present invention describes both a stretch-blow-molded opaque polyester container and a method of making it. The container, typically a beverage bottle has less than 15% transmission of visible light (500 nm) through a 0.4 millimeter wall thickness. It contains from about 0.1 to about 5 wt. % of said opacifying material. The opacifying material may be any material compatible with polyester resin. The method of making the container includes introducing the opacifying material during polymerization, or prepared as a master batch for mixing with the polymer. Selection of certain opacifying materials can also result in favorable reheat properties, gas permeation-barrier improvements, and when the resin contains both opacifying material and oxygen scavenger there can be a synergistic effect with respect to CO2 permeation.