New patent application published for: A PROCESS FOR FORMING A MOULDED PULP FIBRE PRODUCT

A PROCESS FOR FORMING A MOULDED PULP FIBRE PRODUCT

Claims

1-41. (canceled)
42. A process for forming a moulded pulp fibre product, the process comprising: creating a slurry deposit from a suspension of pulp fibres in liquid, reducing the liquid content of the slurry deposit to a liquid fraction within a predefined range to thereby form a pulp fibre pre-form; and pressing the pulp fibre pre-form in a tool set to further reduce the liquid content of the pulp fibre pre-form and thereby deform the pulp fibre pre-form from an initial form to a secondary form, the tool set including at least first and second mould tools that are arranged to move relative to one another between a retracted position in which the separation of the mould tools is a maximum, and a forward position in which the separation of the mould tools is a minimum, at least the first mould tool having a non-planar mould tool surface that includes: one or more primary regions in which the non-planar mould tool surface is to engage the surface of the pulp fibre pre-form while the tool set is pressing the pulp fibre pre-form; and at least one secondary region in which the non-planar mould tool surface is recessed relative to immediately adjacent the primary regions and with respect to movement of the mould tools towards the forward position, the secondary region being surrounded by the primary regions, wherein pressing the pulp fibre pre-form in the tool set comprises: progressing the mould tools towards the forward position to an initial contact position, in which the primary regions that surround the secondary region are in contact with the pulp fibre pre-form and a cavity is formed between at least part of the non-planar mould tool surface within the secondary region and the pulp fibre pre-form, and then at least partially maintaining the cavity as the mould tools continue from the initial contact position towards the forward position such that the portion of the surface of the pulp fibre pre-form that is adjacent the secondary region is unconstrained by the first mould tool.
43. The process of claim 42, further comprising maintaining the cavity between the mould tool surface within the entire secondary region and the pulp fibre pre form, such that the surface of the pulp fibre pre-form that is adjacent the secondary region is unconstrained by the first mould tool throughout the step of pressing the pulp fibre pre-form.
44. The process of claim 42, further comprising maintaining the cavity between only a part of the mould tool surface within the secondary region and the pulp fibre pre form, such that only a portion of the surface of the pulp fibre pre-form that is adjacent the secondary region is unconstrained by the first mould tool throughout the step of pressing the pulp fibre pre-form.
45. The process of claim 43, wherein maintaining the cavity comprises controlling at least one of the rate of movement of the mould tools towards the forward position, and the force applied to at least one of the mould tools.
46. The process of claim 45, wherein controlling the rate of movement of the mould tools towards the forward position comprises limiting the maximum rate of movement to a predefined upper limit.
47. The process of claim 45, wherein controlling the force applied to at least one of the mould tools comprises limiting the maximum force that is applied to a predefined maximum.
48. The process of claim 42, wherein the lateral diameter of the secondary region of the first mould tool is selected such that a diameter-to-material thickness ratio that is equal to or less than 2:1, the diameter-to-material thickness ratio being the ratio of the lateral diameter of the secondary region to the minimum thickness of the pulp fibre pre-form in its initial form.
49. The process of claim 42, wherein the non-planar mould tool surface is configured such that, after the step of pressing the pulp fibre pre-form, the lowest density of the portion that is formed by the secondary region of the first mould tool and the second mould tool is between 50% and 98% of the maximum density of the portions that are formed between the primary regions of the first mould tool and the second mould tool.
50. The process of claim 42, wherein after the step of pressing the pulp fibre pre-form, the density of the portion that is formed by the secondary region of the first mould tool and the second mould tool decreases with distance from portions that are formed between the primary regions of the first mould tool and the second mould tool.
51. The process of claim 42, wherein the second mould tool includes extraction passageways that extend from openings in the mould tool surface of the second mould tool through the second mould tool, and the step of pressing the pulp fibre pre-form comprises applying suction to the extraction passageways to draw liquid from the pulp fibre pre-form through the openings and into the extraction passageways.
52. The process of claim 42, wherein the first mould tool includes venting passageways that extend from openings in the second region of the mould tool surface of the second mould tool through the second mould tool, and the method further comprises allowing gas to discharge from the cavity through the venting passageways during the step of pressing the pulp fibre pre-form.
53. The process of claim 52, further comprising applying suction to the venting passageways to draw gas from the cavity through the venting passageways during the step of pressing the pulp fibre pre-form.
54. The process of claim 42, wherein, in the step of reducing the liquid content of the slurry deposit, the predefined range is a liquid fraction of approximately 33% to 60% by weight of the pulp fibre pre-form.
55. The process of claim 42, wherein the step of pressing the pulp fibre further reduces the liquid fraction such that in the second form of the pulp fibre pre-form has a liquid content of less than approximately 10% by weight of the pulp fibre pre-form.
56. The process of claim 42, further comprising refining the pulp fibre prior to the step of creating the slurry.
57. The process of claim 56, wherein refining the pulp fibre comprises refining the pulp fibre to a Canadian Standard Freeness of less than approximately 300 mL CSF.
58. The process of claim 42, wherein the secondary form of the pulp fibre pre-form is the moulded pulp fibre product.
59. The process of claim 42, wherein the secondary form of the pulp fibre pre-form is an intermediate product in the production of the moulded pulp fibre product.
60. The process of claim 42, wherein the process is arranged to have a material compression ratio that is at least 2:1, wherein the material compression ratio is the ratio of the thickness of the slurry deposit to the minimum thickness of the secondary form of the pulp fibre pre-form, measured in a direction that is parallel to the relative movement of the tool set and at the same relative location of the pulp fibre material.
61. The process of claim 42, wherein pressing the pulp fibre pre-form in the tool set induces propagation of liquid that is within the pulp fibre pre-form in the initial form and is between the primary regions of the first mould tool and the second mould tool, towards the part of the pulp fibre pre-form that is between the secondary region of the first mould tool and the second mould tool.