Plastic Bottle Bottom Design for Freeze-Storage Buckling
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Solution Overview
Problem
Conventional plastic bottles struggle to prevent buckling during freeze-storage of non-sugared beverages due to their high thermal expansion coefficient, and increasing resin usage for strength is not feasible due to resource and cost constraints.
Innovation Solution
A plastic bottle design featuring inwardly protruding valley portions and ground-contacting portions with a partial spherical bottom face, which disperses expansion pressure and reduces toppling risk, while maintaining weight and thickness reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of resin used in the plastic bottle is increased to increase strength, then the buckling phenomenon is suppressed, but the weight and thickness of the plastic bottle increase
Solution Approach 1:
The bottom portion is designed with a curved spherical shape instead of a flat bottom, creating an arched structure that naturally distributes internal pressure from frozen beverage expansion. This geometric curvature provides structural strength equivalent to or greater than flat bottoms with additional resin, while maintaining lightweight construction.
Solution Approach 2:
The plastic bottle employs varying wall thicknesses and structural densities at different locations - the bottom portion features reinforced curved structures where pressure is highest, while other areas maintain thinner walls. This localized strengthening provides necessary buckling resistance without uniformly increasing the bottle's overall weight.
2Strength
If the amount of resin used in the plastic bottle is increased to increase strength, then the buckling phenomenon is suppressed, but the thickness of the plastic bottle increases
Solution Approach 1:
The curved spherical bottom geometry creates an arched load-bearing structure that resists buckling through shape rather than material thickness. The curvature distributes stress across the entire bottom surface, allowing thin-walled construction to achieve the same buckling resistance as thick-walled flat bottoms.
Solution Approach 2:
The bottom portion is divided into multiple structural zones with different thickness profiles - the central curved region provides primary buckling resistance, while peripheral areas have reduced thickness. This segmented approach optimizes material distribution to provide strength where needed while minimizing overall thickness.
3Ease of manufacture
If a conventional flat bottom design is used, then the manufacturing is simple, but the buckling phenomenon occurs during freeze-storage of non-sugared beverages
Solution Approach 1:
The spherical bottom curvature is integrated into the blow-molding manufacturing process through appropriate mold design, allowing the complex curved geometry to be formed in a single operation. Modern plastic molding technology can efficiently produce these curved shapes without significantly increasing manufacturing complexity or cost.
4Loss of substance
If the ground-contacting area is reduced, then the bottle toppling during conveyance increases, but the resource and cost saving goals are achieved
Solution Approach 1:
The curved spherical bottom creates a stable resting position on flat surfaces, with the contact point naturally positioned to minimize toppling moments. The geometry provides inherent stability during conveyance without requiring additional ground-contacting reinforcement structures that would consume extra material.
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
Effectively prevents buckling and toppling of non-sugared beverages during freeze-storage, enhances impact resistance, and allows for favorable moldability and formability, even when frozen.
Implementation Method 1
the thermal expansion coefficient of beverage due to freeze-storage is higher with non-sugared (no sugar-added) drink than with sugared (sugar-added) drink
Implementation Method 2
the deepest part of the valley portion forms an outwardly convex arc extending continuously upwards from the bottom face to the side face, and the bottom face has a partial spherical shape that protrudes inwards
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Provided is a plastic bottle that can effectively resist occurrence of the buckling phenomenon at the time of freeze-storage of non sugared drink while achieving yet desirable weight and thickness reduction of the plastic bottle. A plastic bottle 1 having a cylindrical bottom portion 6 includes a plurality of valley portions 62 protruding inwards from a side face 61 to a bottom face 60 of the bottom portion 6 and a plurality of ground-contacting portions 64. A maximum circumferential length of the ground-contacting portion 64 is set greater than a maximum circumferential length of the valley portion 62 and the deepest part of the valley portion 62 forms an outwardly convex arc 63 extending continuously upwards from the bottom face 60 to the side face 61.