Octagonal PP-EVOH Containers for Deformation-Resistant Sterilization
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Solution Overview
Problem
Plastic containers are not suitable for sterilization processes due to lack of thermal and mechanical resistance, leading to deformation and potential leakage, while glass and metal containers are inefficient in terms of energy consumption and logistics.
Innovation Solution
An octagonal plastic rigid container made through extrusion and thermoforming, with a multilayer structure including polypropylene layers and gas barrier properties, providing enhanced resistance to thermal and mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If plastic containers are used for sterilization processes, then material consumption and energy use are reduced, but the container deforms and leaks due to insufficient thermal and mechanical resistance
Solution Approach 1:
The container uses a multilayer composite structure combining polypropylene (PP) for mechanical strength and heat resistance with EVOH (ethylene vinyl alcohol) layers for gas barrier properties. This composite approach allows the thin-walled container to withstand sterilization temperatures while maintaining structural integrity and preventing leakage, resolving the contradiction between energy efficiency and reliability.
2Reliability
If glass or metal containers are used for sterilization processes, then container integrity is maintained, but energy consumption and manufacturing costs increase
Solution Approach 1:
The invention changes the material parameters by using a multilayer structure with specific thicknesses (total wall thickness 1.5-3.0mm) and material compositions (PP and EVOH layers) that provide both thermal resistance for sterilization and gas barrier properties. This allows plastic containers to achieve the reliability of glass/metal containers while maintaining the energy efficiency and cost advantages of plastic materials.
3Reliability
If injection molding process is used to increase wall thickness for thermal resistance, then sterilization capability is achieved, but material consumption and cost increase
Solution Approach 1:
Instead of increasing wall thickness uniformly through injection molding, the invention uses a multilayer coextruded structure where EVOH barrier layers are distributed within thinner PP layers. This achieves the required thermal and gas barrier properties with reduced total material consumption compared to solid thick-walled injection molded containers.
Solution Approach 2:
The multilayer structure provides localized functionality: PP layers provide mechanical strength and heat resistance where needed, while EVOH layers provide gas barrier properties in specific zones. This localized quality distribution achieves sterilization capability without requiring uniform thick walls throughout the entire container structure.
4Reliability
If additional barrier sleeves are added to injection molded containers, then gas barrier properties are achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention merges the gas barrier function into the container wall structure itself through coextruded EVOH layers, eliminating the need for separate barrier sleeves. This integration reduces device complexity from a multi-component assembly (container + sleeve) to a single monolithic multilayer structure, while maintaining excellent gas barrier properties for extended shelf life.
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 container withstands sterilization processes without deformation, reduces material consumption, and improves logistics efficiency by being stackable, while eliminating the need for additional barrier sleeves.
Implementation Method 1
an octagonal plastic rigid container obtained by extrusion and thermoforming process
Data Source
Figure 1a~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to an octagonal plastic rigid container (1) comprising: a bottom part (2) in an octagonal shape; an upper part (3) in a circular shape; a side wall (4) which is tapered from the upper part towards the lower part; all of them are made of an extruded and thermoformed plastic flat sheet (6-6IV) comprising a first polypropylene "PP" layer (7). Optionally, the sheet further comprises: adhesive layers (8), barrier layers (9), internal layers (11), and several polypropylene "PP" layers (7I - 7VI). The polypropylene layers comprise 40 to 100 weight percent of polypropylene "PP" and/or 2 to about 6 percent by weight of a color concentrate and/or about 5 to about 60 percent by weight of an inorganic reinforcing agent. The container is suitable to be used in packaging process involving some thermal process like the hot-filling, the pasteurization or the sterilization during the food packaging process.