Hourglass Heat-Set PET Container Vacuum Absorption
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Solution Overview
Problem
Conventional heat-set PET containers face challenges in maintaining material integrity and clarity while effectively absorbing internal vacuums, especially during hot-filling processes, due to their cylindrical shape and limited crystallinity.
Innovation Solution
A heat-set PET container with an hourglass shape featuring upper and lower vacuum absorbing regions, forming a reduced waist section, which includes a horizontal reinforcing belt and alternating triangular or trapezoidal vacuum panels, allowing for flexible absorption of internal vacuums and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cylindrical heat-set PET container is used, then the container structure is simple and easy to manufacture, but the container cannot effectively absorb internal vacuums during hot-filling processes
Solution Approach 1:
The container sidewall is segmented into multiple vacuum absorbing regions separated by vertical reinforcing belts. Each vacuum absorbing region contains alternating triangular and trapezoidal vacuum panels that can independently deform to absorb vacuum forces, while the reinforcing belts provide structural support to maintain overall container integrity.
Solution Approach 2:
The container transitions from a conventional symmetric cylindrical shape to an asymmetric design with an hourglass profile. The sidewall features a reduced waist section with varying panel configurations (triangular and trapezoidal) that create asymmetric stress distribution, allowing the structure to better accommodate vacuum forces during hot-filling while maintaining structural integrity.
2Strength
If the PET container crystallinity is increased to improve material integrity, then the container strength improves, but the container clarity deteriorates
Solution Approach 1:
The container employs localized crystalline structures in specific regions rather than uniform crystallization throughout. The vacuum absorbing regions with biaxial molecular orientation maintain higher clarity, while the reinforcing belts and reduced waist section have increased crystallinity for enhanced strength. This localized quality differentiation allows the container to achieve both strength and clarity in different functional areas.
3Weight of moving object
If the container sidewall is made thinner to reduce weight, then the container weight decreases, but the container resistance to creasing during vacuum absorption decreases
Solution Approach 1:
The sidewall is divided into multiple vacuum panels separated by vertical reinforcing belts. This segmentation allows the thinner panel sections to flex and absorb vacuum forces through controlled deformation, while the reinforcing belts provide periodic structural support that prevents excessive creasing. The panelized structure enables weight reduction while maintaining creasing resistance through distributed load bearing.
Solution Approach 2:
The container sidewall is designed with dynamic vacuum absorbing regions that can deform elastically during hot-filling to accommodate vacuum forces. The alternating triangular and trapezoidal panels are configured to flex in a controlled manner, allowing the thin-walled structure to dynamically respond to pressure changes without permanent deformation or excessive creasing.
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 hourglass shape effectively absorbs internal vacuums while maintaining the container's basic structure, enhancing its performance and resistance to creasing, and allowing for higher crystallinity and clarity, suitable for hot-filling and thermal processing.
Implementation Method 1
Thermal processing involves heating the material (either amorphous or semi-crystalline) to promote crystal growth. The thermal processing of an oriented PET container, which is known as heat setting, typically includes blow molding a PET preform against a mold heated to a temperature of approximately 250° F.-350° F. (approximately 121° C.-177° C.), and holding the blown container against the heated mold for approximately two (2) to five (5) seconds.
Implementation Method 2
The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form, also known as the 'crystallinity' of the PET container. Thermal processing involves heating the material (either amorphous or semi-crystalline) to promote crystal growth.
Data Source
AI summary
A heat set container having a shoulder portion and a sidewall portion extending from the shoulder portion to a base. The base closes off an end of the container. The shoulder portion, the sidewall portion, and the base cooperate to define a receptacle chamber within the container into which product can be filled. The sidewall portion defines a major container diameter of the container. The sidewall portion includes an upper vacuum absorbing region joined to a lower vacuum absorbing region at a reduced waist section. The reduced waist section forms a minor container diameter which is less than the major container diameter. In some embodiments, such configuration forms an hourglass, heat-set container, wherein the upper vacuum absorbing region and the lower vacuum absorbing region are collectively shaped to provide flexible absorption of an internal vacuum within the receptacle chamber.