Pulp Fibre Thermoforming Tool With Dual-Layer Fluid Extraction
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Solution Overview
Problem
Existing thermoforming processes for pulp fibre products face limitations due to solubility and porosity, which affect their structural rigidity and barrier properties, particularly in applications like transport and packaging of dry food and electrical/industrial products.
Innovation Solution
A thermoforming tool with displaceable moulds, fluid extraction paths, and a dual-layer structure comprising a rigid first layer and a second layer with interconnected voids and lower heat transfer coefficient, combined with a heating and suction subsystem, to remove moisture and form bonded pulp fibre products with reduced porosity and enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional thermoforming processes are used to form moulded pulp fibre products, then the external surfaces can be smooth and well defined, but the products have limited application due to solubility and porosity
Solution Approach 1:
The patent applies porous materials by incorporating a porous barrier layer within the mould structure that allows controlled fluid extraction while maintaining product integrity. This layer enables the removal of excess water and solvents during the forming process, reducing porosity and solubility of the final product while preserving the smooth external surface quality achieved through traditional thermoforming
Solution Approach 2:
The patent uses composite materials by combining multiple layers with different properties: a smooth external layer for surface quality, a porous barrier layer for fluid extraction, and a structural layer for rigidity. This multi-layer composite approach resolves the contradiction by integrating the benefits of smooth surfaces with the functional advantages of reduced porosity and solubility
2Strength
If wet pulp fibre material is compressed between heated moulds to remove fluid, then bond strength increases, but moisture content remains high affecting structural rigidity
Solution Approach 1:
The patent applies the extraction principle by implementing a fluid extraction system with suction channels that actively remove moisture and other fluids from the pulp fibre material during the bonding process. This extraction mechanism allows the material to achieve adequate bond strength through compression and heating while simultaneously reducing moisture content to levels that ensure proper structural rigidity and dimensional stability
Solution Approach 2:
The patent applies preliminary action by pre-heating the moulds and barrier layers before introducing the wet pulp fibre material. This preliminary heating ensures that when compression begins, the material is already at an optimal temperature for bonding, allowing rapid moisture removal and bond formation to occur simultaneously, thereby achieving both high bond strength and appropriate moisture content for structural rigidity
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 tool effectively reduces moisture content, enhances structural rigidity, and improves oxygen barrier properties of moulded pulp fibre products, achieving performance comparable to commodity polymer-based packaging materials.
Implementation Method 1
the heating subsystem heats the first layer to a temperature that exceeds the liquid-gas transition temperature of the liquid component of the wet pulp fibre material
Implementation Method 2
a suction subsystem that is in communication with the fluid extraction paths and is operable to induce a negative pressure in the fluid extraction paths to thereby draw fluid that is at the moulding surface of the respective mould through the fluid extraction paths
Implementation Method 3
liquid within the wet pulp fibre material migrates into the second layer, within which heat from the first layer causes liquid to change to a gas
Data Source
AI summary
A tool for a thermoforming process to form a moulded product from wet pulp fibre material includes two or more moulds each having a moulding surface, an actuator assembly, and a fluid extraction system. At least one of the moulds is displaceable by the actuator assembly between first and second positions and has fluid extraction paths extending through the mould to transport fluid away from the moulding surface. One of the moulds has a first layer that is substantially rigid to form a support member and is in communication with a heating subsystem of the fluid extraction system, and a second layer that is, in use of the tool, between the first layer and the wet pulp fibre material. The second layer is formed of a material that has interconnected internal voids forming part of the fluid extraction paths and has a lower heat transfer coefficient than the first layer.