PET Dairy Container Structure for Rigidity With Less Material
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Solution Overview
Problem
Existing plastic containers for small liquid dairy products, such as those made from HDPE and polystyrene, face challenges in recyclability and cost due to high material thickness and recycling complexity, leading to increased production costs and environmental impact.
Innovation Solution
Designing containers from polyethylene terephthalate (PET) with optimized dimensions and structural features, including annular stiffeners and a concave central dome, allowing for low-pressure blowability and high manufacturing rates while maintaining rigidity and low weight, using a mold with half-molds for precise shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If containers are made from HDPE or polystyrene with high material thickness, then strength and rigidity are improved, but recyclability deteriorates and production cost increases
Solution Approach 1:
The patent changes the material parameter from HDPE/polystyrene to PET, which has different mechanical properties and recycling characteristics. PET allows for thinner wall designs while maintaining adequate strength, and importantly, PET has superior recyclability compared to HDPE and polystyrene, enabling closed-loop recycling systems.
Solution Approach 2:
The patent applies local reinforcement features (annular stiffeners, radial stiffeners, and bottom arch design) to specific locations where structural strength is needed, rather than uniformly thickening the entire container wall. This allows the container to achieve required rigidity with minimal material usage, reducing both cost and recycling complexity.
2Strength
If material thickness is increased to improve container strength, then rigidity is improved, but material cost and production complexity increase
Solution Approach 1:
The patent implements localized reinforcement through annular stiffeners positioned at specific heights, radial stiffeners extending from the bottom, and an arched bottom design. These features concentrate material only where structurally necessary, achieving high rigidity with minimal overall material consumption.
Solution Approach 2:
The patent employs curved geometric features including the arched bottom design and rounded transitions in the container profile. These curved structures inherently provide greater structural strength per unit of material compared to flat designs, improving rigidity while reducing material requirements.
3Productivity
If container height is reduced to improve blowability, then manufacturing speed is improved, but volume capacity is reduced
Solution Approach 1:
The patent utilizes the excellent formability of PET material to create a container with optimized proportions that balance blowability and capacity. The material's flexibility during molding allows for efficient geometric configurations that maximize volume within the height constraints required for high-speed manufacturing.
Solution Approach 2:
The patent employs optimized curved profiles and smooth transitions in the container geometry, which improve blowability during manufacturing while maximizing internal volume. The curved design allows for efficient material distribution and air flow during the blow-molding process, enabling faster production without sacrificing capacity.
4Ease of manufacture
If PET material is used with optimized dimensions, then recyclability and material efficiency are improved, but structural strength may be reduced
Solution Approach 1:
The patent applies localized reinforcement features (annular stiffeners, radial stiffeners, and bottom arch design) to specific locations where structural strength is needed, rather than uniformly thickening the entire container wall. This allows the container to achieve required rigidity with minimal material consumption, making PET a viable choice while maintaining recyclability.
Solution Approach 2:
The patent effectively creates a composite structure by combining PET material with integrated reinforcement features molded as part of the container. The annular and radial stiffeners work together with the bottom arch to create a synergistic structural system that provides enhanced rigidity while maintaining the recyclability of the base PET 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
The PET containers achieve low-cost, high-speed production with reduced material usage, excellent recyclability, and improved rigidity, while maintaining good blowability and grip, making them economically viable and environmentally friendly.
Implementation Method 1
the preform is heated until its constituent material reaches or exceeds its glass transition temperature. For example, if the container is made of polyethylene terephthalate, the glass transition temperature is around 70° C. and may approach 80° C.
Implementation Method 2
the preform is simultaneously stretched by a stretching rod and inflated by a gas injected at an overpressure
Data Source
AI summary
Provided is a container obtained by blow molding or stretch blow molding from a preform made of polyethylene terephthalate and manufacturing methods of containers. The container includes a body, a shoulder extending the upper end of the body, a neck extending from the shoulder, and a bottom which extends at a lower end of the container. The neck can be open and form a rim of the container. The container can be intended to receive a liquid or semi-liquid dairy product such as milk, which can be distributed through a cold chain or at ambient temperature.