Pulp Bottle Moulding with Inflatable Bladder Dewatering
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Solution Overview
Problem
Existing technologies face challenges in forming complex liquid-holding containers from paper pulp, as they struggle to achieve uniform wall thickness and efficient liquid removal, particularly for bottles and jars.
Innovation Solution
A method involving a porous mould for forming a fibre suspension, followed by an inflatable bladder to apply internal pressure, and a non-porous mould for further shaping and drying, combined with microwave drying and protective coating, to create a one-piece pulp bottle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a porous mould is used to form fibre suspension, then liquid removal is enabled, but uniform wall thickness and complex shapes are difficult to achieve
Solution Approach 1:
The moulding process is divided into two distinct stages: first using a porous mould for liquid removal, then transferring to a non-porous mould for precision shaping. This segmentation allows each mould type to excel at its specific function without compromise.
Solution Approach 2:
An impermeable pressing member (bladder) acts as an intermediary tool that transfers the fibre-mould assembly from the porous mould to the non-porous mould, enabling the transition between the two moulding stages.
2Object-generated harmful factors
If an impermeable pressing member is inserted into the mould to apply pressure, then further liquid expulsion is achieved, but mould complexity increases
Solution Approach 1:
The impermeable pressing member is implemented as a flexible bladder that can be inflated to apply uniform pressure against the fibre suspension, effectively expelling remaining liquid while maintaining simplicity through the use of a flexible membrane rather than rigid mechanical components.
3Manufacturing precision
If the article is transferred to a non-porous mould for further shaping, then shape precision is improved, but process complexity increases
Solution Approach 1:
The moulding process is divided into two distinct stages: first using a porous mould for liquid removal, then transferring to a non-porous mould for precision shaping. This segmentation allows each mould type to excel at its specific function without compromise.
Solution Approach 2:
The fibre suspension is initially formed in the porous mould, then the entire assembly (mould plus fibre content) is nested within the non-porous mould for the second shaping stage, allowing sequential processing without removing the 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 method produces a strong, uniform, and recyclable pulp bottle with efficient liquid removal and drying, suitable for holding liquids, while reducing plastic use.
Implementation Method 1
The mould has openings through it or is porous such that a suspending liquid introduced to the mould, with which the pulp is mixed, can be removed by applying suction
Implementation Method 2
a suspending liquid introduced to the mould, with which the pulp is mixed, can be removed by applying suction
Implementation Method 3
an impermeable surface (e.g. an inflatable bladder in a collapsed state) is inserted into the wet moulded article to apply pressure to internal walls of the article (e.g. by inflation with pneumatic or hydraulic pressure; air, water or oil) and thereby expel further suspending liquid through pores of the porous mould
Implementation Method 4
in order to impart the shape of the non-porous mould to external walls of the article. Such a step is preferably heated to 'thermoform' and drive out remaining suspending liquid and strengthen walls of the moulded article by compression and drying
Implementation Method 5
strengthen walls of the moulded article by compression and drying
Implementation Method 6
A drying stage of the method/system may utilise microwave energy, e.g. in a continuous or batch delivery system
Data Source
AI summary
A system and method of producing a moulded article, e.g. a one-piece container, comprises delivering a fibre suspension to a porous mould and removing a suspending liquid (e.g. water) via pores of the porous mould. An inflatable bladder is inserted into the mould in a collapsed state and then inflated to apply pressure to internal walls of the article to remove water content. A wet embryonic form of the container is then transferred to a non-porous mould where an inflatable bladder applies internal pressure to compress the walls and remove further water content. The container is further dried by microwave and/or air drying and may be coated with a protective layer.