MFC Screw Cap Forming via Thermal Shrinkage
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Solution Overview
Problem
The use of polyethylene screw caps in cardboard packages for liquid or semi-liquid food increases plastic content, which is not biodegradable and contributes to environmental issues, while existing alternatives like microfibrillated cellulose (MFC) bio nanocomposites in screw caps are not widely adopted due to manufacturing challenges.
Innovation Solution
A method involving pre-preg microfibrillated cellulose (MFC) is used, where a piece of MFC with 40-90% dryness is placed between two tools with protruded and inner lateral surfaces, heated between 50-200°C to form a screw cap with inner threads, and then unscrewed, eliminating the need for plastic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyethylene screw caps are used in cardboard packages, then the opening can be resealed to keep food fresh, but the amount of plastics in the package is increased
Solution Approach 1:
The patent changes the material parameter from synthetic polyethylene to natural microfibrillated cellulose (MFC), transforming the screw cap from a plastic-based to a biodegradable material while maintaining the essential resealability function through controlled drying and shrinking processes
Solution Approach 2:
The invention replaces durable plastic screw caps with biodegradable MFC screw caps that can be composted after use, converting a long-lasting non-biodegradable object into a short-living biodegradable one that returns to the environment, thus reducing plastic accumulation
2Quantity of substance
If microfibrillated cellulose (MFC) is used to manufacture screw caps, then plastic usage is reduced and biodegradability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-drying the MFC material to a specific moisture content (40-90%) before forming, and by pre-heating the tools to controlled temperatures (50-200°C) to ensure proper drying and shrinking during the forming process, thereby simplifying the overall manufacturing control
Solution Approach 2:
The invention utilizes parameter changes by controlling the moisture content of MFC during forming and using temperature-controlled drying (50-200°C) to make the material shrink and conform to the tool geometry, transforming the manufacturing process from complex multi-step to a controlled thermal-drying process
3Manufacturing precision
If MFC is heated to form the screw cap, then the material dries and shrinks to form the final shape, but energy consumption increases
Solution Approach 1:
The patent optimizes the heating parameters by controlling temperature within 50-200°C and monitoring moisture content (40-90% dryness) to achieve proper drying and shrinking, allowing energy-efficient processing that maintains form accuracy without excessive energy input
Solution Approach 2:
The invention applies dynamics by using progressive heating and controlled drying rates, allowing the MFC material to gradually shrink and conform to the tool geometry rather than rapid heating, thereby achieving precise forming with optimized energy consumption
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
This method effectively reduces plastic usage by creating a biodegradable screw cap with MFC, enhancing sustainability and maintaining resealability for food freshness.
Implementation Method 1
heating the first and the second tool to a temperature between 50-200°C, preferably 100-170°C, such that the piece of pre-preg MFC dries and shrinks onto the first tool
Implementation Method 2
heating the first and the second tool to a temperature between 50-200°C, preferably 100-170°C, such that the piece of pre-preg MFC dries and shrinks onto the first tool
Data Source
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AI summary
The present invention relates to a method for manufacturing a screw cap(12), wherein the screw cap having a blind hole with inner threads. The method comprising the steps of placing a piece pre-preg MFC (11), of a suitable size for forming the screw cap, between a first tool (1) comprising a protruded part (2) with outer threads (4) for forming the inner threads (17) of the blind hole (14),and a second tool comprising a section (22) with an inner lateral surface (25) for forming an outer lateral surface(18) of the screw cap, moving the protruded part of the first tool into the section of the second tool, such that,the first and the second tool forms the screw cap,drying the piece of pre-preg MFC, such that it is shrinks onto the first tool and thereby forms the screw cap, and unscrewing the formed screw cap from the threads of the protruded part of the first tool.