Mould for forming a unitary article from pulp
A mould ( 14 ) for forming an article from a fibre suspension. The mould includes an insert with a cavity ( 27 ) in the negative shape of an article to be formed and two regions of different porosity/permeability ( 28, 29 ) about the cavity ( 27 ). In use the mould communicates a suspending fluid of the fibre suspension, e.g. by vacuum pump, through the at least two regions of different porosity/permeability about the cavity. A formed shape ( 22 ) of fibres is left behind on the cavity.
1 . A mould for forming a bottle shaped article from a fibre suspension, the mould comprising:
a cavity in a negative shape of the bottle shaped article to be formed;
wherein the mould is configured to communicate a suspending fluid of the fibre suspension through at least two volumetric regions of different porosity about the cavity;
wherein a first porous region, having a porosity greater than 0% and less than or equal to 90%, is a first layer comprising a criss-cross structure of a consistent mesh and constitutes the substantive article facing surface of the cavity, and a second porous region, having a porosity greater than the first porous region but less than 100%, is a second layer serving as a supporting structure for the first porous region, the first porous region and the second porous region being configured to cause an overall pressure drop through the mould;
wherein porosity denotes the ratio of void volume to total volume of the first porous region and the second porous region.
2 . The mould of claim 1 , comprising a third porous region in communication with the first and second porous region.
3 . The mould of claim 1 , wherein the mould is a removeable insert for insertion into a mould block.
4 . The mould of claim 3 , wherein the removeable insert is 3-D printed or made by another additive manufacturing technique.
5 . The mould of claim 1 , wherein the porosity of the first porous region is 40%-70% and the porosity of the second porous region is 80-90%.
6 . The mould of claim 1 , wherein the mould comprises two or more cooperating pieces, each including a portion of the cavity, configured to open apart for removal of a moulded article.
7 . The mould of claim 1 , comprising an opening into the cavity for receiving a fibre suspension dispenser nozzle.
8 . The mould of claim 7 , in combination with a fibre suspension dispenser nozzle, wherein the cavity is configured for moulding a bottle comprising a neck, shoulder and main body; the fibre suspension dispenser nozzle comprising a tube extendable through the opening, to a position proximate the shoulder.
9 . A method of moulding an article, comprising:
preparing a fibre suspension in a suspending liquid;
feeding the fibre suspension to the mould according to claim 1 ;
removing the suspending liquid through the at least two regions of different porosity;
applying pressure to internal walls of the article, in order to expel further suspending liquid through the at least two regions of different porosity; and
removing the moulded article from the mould.
10 . The method of claim 9 , comprising cleaning walls of the mould after removal of the article.
11 . The method of claim 10 , wherein cleaning comprises reversing expelled suspending liquid back through the mould and/or use of a water jet against walls of the mould.
12 . The method of claim 9 , wherein the fibre suspension fed to the porous mould comprises 0.1 to 1% solids.
13 . The method of claim 12 wherein the fiber suspension fed to the porous mould comprises 0.7% solids.