A PICK-UP PRESS DEVICE AND METHOD OF PRODUCING A 3D-MOLDED PRODUCT FROM A PULP SLURRY

Abstract

The document relates to a pick-up press device for use in a process of producing a 3D molded product from a pulp slurry comprising a pick-up press tool presenting a porous first product face; a press tool presenting a second product face; and a vacuum source, connected to the pick-up press tool. The pick-up press tool and the press tool are vertically movable relative one another, wherein, in a first relative position of the press tools, at least one of the product faces is positioned so as to receive a pulp slurry layer in liquid form to its product face, and wherein in a second relative position of the press tools, the product faces are pressed towards each other for pressing the pulp slurry layer. The device further comprises a first transfer tool, wherein the first transfer tool comprises a first forming surface portion, configured to conform to a first portion of the porous first product face, such that a forming gap is defined there between, said forming gap defining a desired pulp slurry layer thickness; and a second forming surface portion, configured to diverge from a second portion of the porous first product face, such that a non-forming space is defined by the second forming surface portion and a second portion of the porous first product face, said non-forming space having a greater thickness than the forming gap.

Claims

1-49. (canceled)

50. A pick-up press device for use in a process of producing a 3D molded product from a pulp slurry comprising: a pick-up press tool presenting a porous first product face, a press tool presenting a second product face, and a vacuum source, connected to the pick-up press tool, wherein the pick-up press tool and the press tool are vertically movable relative one another, wherein, in a first relative position of the press tools, at least one of the product faces is positioned so as to receive a pulp slurry layer in liquid form to its product face, and wherein in a second relative position of the press tools, the product faces are pressed towards each other for pressing the pulp slurry layer, wherein the device further comprises a first transfer tool, wherein the first transfer tool comprises: a first forming surface portion, configured to conform to a first portion of the porous first product face, such that a forming gap is defined there between, said forming gap defining a desired pulp slurry layer thickness, and a second forming surface portion, configured to diverge from a second portion of the porous first product face, such that a non-forming space is defined by the second forming surface portion and the second portion of the porous first product face, said non-forming space having a greater thickness than the forming gap.

51. The pick-up press device according to claim 50, wherein the pick-up press tool is provided with at least one heating element adapted to supply heat to the porous first product face of the pick-up press tool and/or the press tool is provided with at least one heating element adapted to supply heat to the second product face of the press tool.

52. The pick-up press device according to claim 51, wherein in the second relative position of the press tools, the product faces are pressed towards each other for pressing the pulp slurry layer, while heating the pulp slurry layer by means of the at least one heating element and drawing a vacuum through a porous product face of at least one of the tools.

53. The pick-up press device according claim 50, wherein the non-forming space is configured to provide contact between only one pulp slurry layer face and one of the second forming surface portion and the second portion of the porous first product face.

54. The pick-up press device according to claim 50, wherein the non-forming space presents a space between the second forming surface portion and the second portion of the porous first product face, that is greater than 20× a thickness of the forming gap.

55. The pick-up press device according to claim 50, wherein the non-forming space presents a space between the second forming surface portion and the second portion of the porous first product face, that is greater than 15× of said thickness of the forming gap.

56. The pick-up press device according to claim 50, wherein the non-forming space is provided at an innermost portion of a female mold and/or at a distal portion of a male mold, as seen in the press direction.

57. The pick-up press device according to claim 50, wherein the non-forming space is provided at an outermost portion of a female mold and/or at a distal portion of a male mold, as seen in the press direction.

58. The pick-up press device according to claim 50, wherein the forming gap presents a thickness that is small enough for both the first forming surface portion and the first portion of the porous first product face to contact a respective pulp slurry layer face.

59. The pick-up press device according to claim 50, wherein the first forming surface portion presents a contact surface area corresponding to 10-99.9% of the total area of the porous first product face.

60. The pick-up press device according to claim 50, wherein the first transfer tool presents a porous product face having a porosity of 10-90%.

61. The pick-up press device according to claim 60, wherein the porous product face of the first transfer tool presents pores with a hole size of 0.1-0.7 mm in diameter.

62. A method of producing a 3D molded product from a pulp slurry, comprising: applying, in liquid form, a pulp slurry layer to a porous first product face of a pick-up press tool of a first mold, in a first forming step, pressing the pulp slurry layer on the porous first product face of the pick-up press tool against a second product face of a cooperating press tool of the first mold, while heating the pulp slurry layer and drawing a vacuum through a porous product face of at least one of the tools, transferring the pulp slurry layer to a porous product face of a first press tool of a second mold, in a second, subsequent, forming step, pressing the pulp slurry layer against a second product face of a second press tool of the second mold, while heating the pulp slurry layer and drawing a vacuum through a porous product face of at least one of the first and second press tools of the second mold, wherein at least a portion of the pulp slurry layer is formed during the transfer to the first press tool of the second mold.

63. The method as claimed in claim 62, wherein the transfer of the pulp slurry layer from the first mold to the second mold is performed by means of a first transfer tool, the first transfer tool comprising a first forming surface portion and a second forming surface portion, wherein, during a transfer of the pulp slurry layer from the first mold to the first transfer tool, the first forming surface portion conforms to a first portion of the porous first product face of the first mold, such that a forming gap is defined there between, said forming gap defining a desired pulp slurry layer thickness, and wherein the second forming surface portion diverges from a second portion of the porous first product face of the first mold, such that a non-forming space is defined by the second forming surface portion and the second portion of the porous first product face of the first mold, said non-forming space having a greater thickness than the forming gap.

64. The method according to claim 63, wherein, during a transfer of the pulp slurry layer from the first mold to the first transfer tool, the forming gap provides a pressure on the pulp slurry layer that is greater than ambient pressure.

65. The method as claimed in claim 63, wherein, during a movement of the first transfer tool from the first mold to the second mold, the first forming surface portion is in contact with a pulp slurry layer face and the second forming surface portion is free.

66. The method as claimed in claim 62, wherein during the transfer of the pulp slurry layer from the first mold to the second mold, a vacuum is drawn through the first transfer tool such that at least some water is evacuated from the pulp slurry layer.

67. The method as claimed in claim 62, wherein the pulp slurry layer transferred to the second mold presents a first pulp slurry layer portion and a second pulp slurry layer portion, wherein the first and second pulp slurry layer portions are juxtaposed and the first pulp slurry layer portion has a higher or lower level of water content than the second pulp slurry layer portion.

68. A method of forming a receptacle, comprising the method as claimed in claim 62, wherein the non-forming space is provided at a respective portion of a press tool and transfer tool corresponding to an opening portion of the receptacle.

69. A system for producing a 3D molded product from a pulp slurry comprising: a pick-up press device according to claim 50, and a second pair of cooperating press tools.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIGS. 1a-1d schematically illustrate a pair of pick-up press tools of a pick-up press device.

[0096] FIGS. 2a-2d schematically illustrates a transfer tool of a pick-up press device

[0097] FIG. 2e schematically illustrates a pair of press tools.

[0098] FIG. 2f-2g schematically illustrates two different embodiments of a transfer tool of a pick-up press device.

[0099] FIG. 3 schematically illustrates a production process.

DETAILED DESCRIPTION

[0100] FIG. 1a schematically illustrates a pick-up press tool 10, a cooperating press tool 20, and a container 1 with a pulp slurry 2.

[0101] The pick-up press tool 10 is adapted to both pick up a pulp slurry layer 3 from a pulp slurry 2, and press the pulp slurry layer 3 in a first pressing step.

[0102] The pick-up press tool 10 is mounted to a tool holder 11, which together with the pick-up press tool defines a vacuum chamber 12 that is connected to a pressure regulator P1. The pressure regulator may have the capability of selectively generating an at least partial vacuum (i.e. air pressure lower than ambient air pressure) and/or an air pressure greater than ambient air pressure.

[0103] The pick-up press tool can be self-supporting, meaning that a tool wall portion of the tool is sufficiently rigid and has a melting point that is sufficiently high for the tool wall portion not to require any support structure for maintaining its shape during operation.

[0104] The pick-up press tool 10 presents a porous first product face, i.e. a porous surface of the tool that is adapted to be in contact with a pulp slurry layer or pulp product during forming of such a pulp product. The porosity of the porous first product face may be 10-90%.

[0105] The porous first product face may further present pores with a hole size of 0.1-0.7 mm in diameter, preferably 0.25-0.6 mm.

[0106] As illustrated in FIG. 1a, the press tool 20 can also be mounted to a tool holder 21. The tool holder 21 can together with the press tool 20 define a vacuum chamber 21. The vacuum chamber 21 can be connected to a pressure regulator P2. The pressure regulator may have the capability of selectively generating an at least partial vacuum (i.e. air pressure lower than ambient air pressure) and/or an air pressure greater than ambient air pressure.

[0107] The press tool 20 presents a second product face. The second product face may be porous or non-porous. Alternatively, the second product face may present porous portions and non-porous portions.

[0108] The pick-up press tool 10 and press tool 20 are vertically movable relative one another.

[0109] In a first relative position of the press tools 10, 20, at least one of the product faces is positioned so as to receive the pulp slurry 3, which can be in liquid form, to its product face, see FIG. 1a.

[0110] In a second relative position of the press tools 10, 20, the product faces are pressed towards each other for pressing the pulp slurry layer, see FIG. 1d.

[0111] Consequently, the pick-up press tool 10 can maintain its orientation in relation to the press tool 20 from the pick-up of the pulp slurry layer to the pressing of pulp slurry layer.

[0112] Further, the pick-up press tool 10 can be moved in a direction Y1 for imitating the step of picking up the pulp slurry layer 3 from the container 1 with the pulp slurry 2, see FIG. 1a.

[0113] Further, the pick-up press tool 10 can be moved in a direction Y2 for initiating the step of pressing the pulp slurry layer 3 in the first pressing step, see FIG. 1c.

[0114] Alternatively, or additionally, the press tool 20 may be moved in the direction Y1 for initiating the first pressing step.

[0115] FIG. 1b schematically illustrates the pick-up press tool 10 immersed in the container 1 holding the pulp slurry 2. While the pick-up press tool is immersed in the pulp slurry 2, the pressure regulator P1 may generate a vacuum, causing pulp fibers 3 to be drawn towards a product face of the pick-up press tool 10.

[0116] FIG. 1c schematically illustrates the pick-up press tool 10 moving the pulp fibers 3 towards the press tool 20, i.e. initiating the first pressing step.

[0117] During the movement, the pressure regulator P1 may generate a vacuum, causing pulp fibers 3 to stick to the product face of the pick-up press tool 10.

[0118] FIG. 1d schematically illustrates the pick-up press tool 10 and the press tool 20 in a pressing position. Consequently, the pick-up press tool 10 and the press tool 20 can form a pressing arrangement adapted to perform a first pressing step of the pulp slurry layer 3.

[0119] The pick-up press tool 10 and the press tool 20, and their associated tool holders 11, 21, are movable relative one another between an open position, and the pressing position. In the pressing position, as illustrated in FIG. 1d, the tools 10, 20 are forced towards each other, thus pressing the pulp slurry layer between the product faces of the respective tool 10, 20, such that a pulp product 3′ is formed.

[0120] As illustrated in FIG. 1d, one, or both of the pick-up press tool and the press tool may be supplied with a heating element 13, 23. The heating elements are adapted to supply heat to the product faces of the tools.

[0121] The heating elements can be energized by an energy supply E1, E2. Further, the heating elements can be controlled by a controller C.

[0122] The heating element may be an electric heating element, hot air or liquid heating element, or induction heating element.

[0123] When in the pressing position, heat may be supplied by one, or both, of the heating elements 13, 23.

[0124] During the pressing of the pulp product 3′, one or both pressure regulators P1, P2 may provide a vacuum to assist in the evacuation of water vapor from the pulp product 3′.

[0125] As an alternative, one of the pressure regulators P1, P2 may provide a vacuum while the other one provides a pressure greater than the ambient air pressure.

[0126] Optionally, hot air or steam may be introduced through the tools during the pressing process (FIG. 1d).

[0127] As an alternative to immersing the pick-up press in the pulp slurry, the pulp slurry can be applied by a coating operation, such as spray coating or pouring. Optionally, during the coating operation the pressure regulator P1 may generate a vacuum, causing pulp fibers 3 to be drawn towards the product face of the pick-up press tool 10.

[0128] It is also noted that two or more successive pressing steps may be used, e.g. to gradually form all or parts of the product 3′, 3″, 3′″ and/or to apply additional features to the product, such as coatings, decors and the like.

[0129] FIG. 2a-2d illustrates a first transfer tool 30 that can be used to transfer the product 3′ from the first press tools 10, 20 to a second pair of press tools 40, 50, see. FIG. 2a-2e.

[0130] The first transfer tool 30 may be connected to a third pressure regulator P3, which is capable of generating a vacuum or an air pressure. The transfer tool 30 may also be mounted on a transfer tool holder 31 so as to define a vacuum chamber 32, which is connected to the third pressure regulator P3.

[0131] During the transfer of the pulp fibers, an air pressure greater than ambient pressure may be generated by the first pressure regulator P1 to cause the pulp fibers to release from the pick-up press tool 10.

[0132] Alternatively, or as a supplement, a vacuum may be generated by the third pressure regulator P3, causing the pulp fibers to be received by the transfer tool 30.

[0133] The first transfer tool may be supplied with a heating element (not illustrated). The heating element is adapted to supply heat to a product face of the first transfer tool. The heating element can be energized by an energy supply. Further, the heating element can be controlled by a controller C.

[0134] The heating element may be an electric heating element, hot air or liquid heating element, or induction heating element.

[0135] The first transfer tool 30 is adapted to form part of the product 3′, as illustrated in FIG. 2a-2d.

[0136] The first transfer tool 30 can present a porous product face.

[0137] The porous product face of the first transfer tool 30 may have a porosity of 10-90%.

[0138] The porous product face of the first transfer tool 30 may present pores with a hole size of 0.1-0.7 mm in diameter, preferably 0.25-0.6 mm.

[0139] As illustrated in FIGS. 2a and 2b, the first transfer tool 30 can comprise a first forming surface portion 34 and a second forming surface portion 35.

[0140] As illustrated in FIG. 2a, the first forming surface portion 34 can be configured to conform to a first portion 14 of the porous first product face, such that a forming gap 80 is defined there between. The forming gap 80 can define a desired pulp slurry layer thickness.

[0141] The second forming surface portion 35 can be configured to diverge from a second portion 15 of the porous first product face, such that a non-forming space 90 is defined by the second forming surface portion 35 and a second portion 15 of the porous first product face. The non-forming space 90 can have a greater thickness than the forming gap 80.

[0142] The non-forming space 90 can be configured to provide contact between only one pulp slurry layer face and one of the second forming surface portion 35 and the second portion 15 of the porous first product face.

[0143] The non-forming space 90 can present a space between the second forming surface portion 35 and the second portion 15 of the porous first product face, that is greater than 20× a thickness of the forming gap 80, preferably greater than 15×, greater than 10×, or greater than 5× said thickness of the forming gap 80.

[0144] The non-forming space 90 can be provided at an innermost portion of a female mold and/or at a distal portion of a male mold, as seen in the press direction, see FIG. 2f.

[0145] Alternatively, the non-forming space 90 can be provided at an outermost portion of a female mold and/or at a distal portion of a male mold, as seen in the press direction, see FIG. 2g.

[0146] The female mold may be a pick-up press tool or a press tool. The male mold may be a transfer tool.

[0147] The forming gap 80 can present a thickness that is small enough for both the forming surface portion 34 and the first portion 14 of the porous first product face to contact a respective pulp slurry layer face.

[0148] The forming gap 80 can be configured to provide a pressure on the pulp product 3′ that is greater than ambient pressure.

[0149] Consequently, as the pulp product 3′ is transferred from the porous first product face of the pick-up press tool 10 to the first transfer tool 30, see FIG. 2a, a pressure greater than ambient pressure may be applied to a portion of the pulp product 3′ that is in contact with both the forming surface portion 34 of the first transfer tool 30 and the first portion 14 of the porous first product face.

[0150] The first forming surface portion 34 can be adapted to be in contact with a portion of the product 3′ during a transfer of the product.

[0151] The first forming surface portion 34 can present a contact surface area that is sufficient for receiving and retaining the pulp product 3′ at the first transfer tool during a movement of the first transfer tool.

[0152] The first first forming surface portion 34 can present a contact surface area corresponding to 10-99,9% of the total area of the porous first product face, preferably 25-95%.

[0153] As illustrated in FIG. 2b, at least a portion of the pulp product 3′ can be free during the movement of the first transfer tool from the first press tools 10, 20 to the second pair of press tools 40, 50.

[0154] Consequently, during a movement of the first transfer tool, transferring the pulp product 3′ from the first pair of press tools 10, 20 to the second pair of press tools 40, 50, the first forming surface portion 34 can be in contact with a pulp slurry layer face and the second forming surface 35 can be free.

[0155] The shape of the porous product face of the first transfer tool 30 can substantially match the shape of a product face of a press tool of the second pair of press tools, see FIG. 2c.

[0156] Consequently, as the pulp product 3′ is transferred to the product face of the press tool 40, the at least one free portion of the pulp product 3′ can be brought into contact with second forming surface portion 35 of the first transfer tool 30. The at least one free portion of the pulp product 3′ can thereby be formed as the pulp product 3′ is transferred from the first transfer tool 30 to the product face of the press tool 40, see FIG. 2c.

[0157] The first transfer tool 30 can then be removed from the press tool 40, as illustrated in FIG. 2d. Then the pulp product 3″ can be pressed in a second pressing step, using the second pair of press tools 40, 50, as illustrated in FIG. 2e.

[0158] A vacuum may be generated by the third pressure regulator P3 when the first transfer tool 30 transfers the product from the pick-up press tool 10 (FIG. 2a), causing the pulp fibers to be received by the transfer tool 30. Additionally or alternatively, a vacuum may be generated during the movement of the first transfer tool 30, from the first pair of press tools 10, 20 to the second pair of press tool 40, 50. Consequently, water may be evacuated from the product during the transfer.

[0159] As the first transfer tool 30 is adapted such that at least one portion of the pulp product 3′ can be in contact with the porous product face of the first transfer tool 30 during the transfer, and at least one portion of the pulp product 3′ can be free, i.e. not in contact, different levels of water may be evacuated from different portions of the pulp product 3′.

[0160] Consequently, the pulp product 3′ transferred to the second pair of press tools 40, 50 can present a first pulp slurry layer portion and a second pulp slurry layer portion, wherein the first and second pulp slurry layer portions are juxtaposed and the first pulp slurry layer portion has a higher or lower level of water content than the second pulp slurry layer portion.

[0161] A second transfer tool may be used to transfer the pulp product 3′″ from the second pair of press tools 40, 50 to a third pair of press tools (not illustrated).

[0162] The second transfer tool may be designed essentially the same as the first transfer tool or have a different design. Consequently, the second transfer tool may be used to transfer the product from the second pair of press tools to a third pair of press tools, or alternatively both transfer and form part of the product.

[0163] According to the present invention, a pick-up press device for use in a process of producing a 3D molded product from a pulp slurry is provided comprising a pick-up press tool, a press tool, a vacuum source connected to the pick-up press tool, and a first transfer tool, in accordance with what has been described with respect to FIGS. 1a-1d and FIG. 2a-2e.

[0164] According to the present invention, a method of producing a 3D molded product from a pulp slurry is also provided.

[0165] In one embodiment, steps are performed in accordance with what has been described with respect to FIGS. 1a-1d and FIG. 2a-2c.

[0166] The 3D molded product may be a receptacle, such as for example a container, cup, jar, tin, bottle etc. adapted to contain a solid, liquid and/or gaseous content.

[0167] The non-forming space 90 can then be provided at a respective portion of a press tool and transfer tool, corresponding to an opening portion of the receptacle. The opening portion may present a rim of the receptacle.

[0168] Referring to FIG. 3, a production process will now be described.

[0169] In a first step 101, a pulp slurry layer is provided, e.g. as described with reference to FIG. 1a, wherein a pulp slurry layer is applied to a porous first product face of a first mold. This may be achieved by providing a first mold comprising a pick-up press tool, presenting the porous first product face, and a press tool, presenting a second product face. The second product face may be porous or non-porous. Alternatively, the second product face may present porous portions and non-porous portions.

[0170] The pick-up press tool may be adapted to, in the step of applying a pulp slurry layer to the porous first product face, pick up a pulp slurry layer from a pulp slurry.

[0171] The picking up of the pulp slurry layer may be performed by immersing a porous pick-up press tool of the first mold in a pulp slurry, with vacuum being applied to a rear side of the pickup-press tool.

[0172] A first pressure at a rear side of the porous first product face during the pick-up of the pulp slurry layer can be 300-700 mbarA (millibar absolute), preferably 400-600 mbarA.

[0173] A flow through the tool can be between 50 and 1000 m.sup.3/h. Preferably the flow can be between 1000 and 30 000 m.sup.3/h per square meter of the porous first product face of the tool.

[0174] Consequently, a vacuum can be drawn through the porous first product face of the pick-up press tool, such that a pulp slurry layer can be applied to the porous first product face.

[0175] The porous first product face of the pick-up press tool may have a surface porosity of 10-90% with hole sizes 0.1-0.7 mm in diameter, preferably 0.25-0.6 mm.

[0176] Alternatively, the pulp slurry may be applied to the pick-up press tool by a coating operation, such as spray coating or pouring. Optionally, during the coating operation a vacuum may be drawn through the porous first product face of the pick-up press tool, causing pulp fibers to be drawn towards the product face of the pick-up press tool.

[0177] In a second step 102, the pulp slurry layer is pressed in the first mold. Consequently, the pick-up press tool with the pulp slurry layer is raised from the pulp slurry or it's initial coating position, and moved towards the press tool, whereby the pulp slurry layer is pressed against the second product face of the press tool. This may be performed in one vertical movement, such that the pick-up press tool is raised and moved directly to the press tool.

[0178] Alternatively the pick-up press tool may be raised from the pulp slurry and the press tool is moved to the pick-up press tool.

[0179] Alternatively, both the pick-up press tool and the press tool may be moved in a vertical direction towards each other.

[0180] In this first pressing step 102, a pressure lower than the surrounding ambient pressure is applied at a rear side of a porous product face of the first mold, thus resulting in a vacuum at the rear side of the porous product face, causing solvent vapor, such as steam, to be drawn through the tool.

[0181] The pressure applied to the rear side of the porous product face may be on the order of low or medium level vacuum. That is, a first pressure may be 200-900 mbarA, preferably 300-800 mbarA.

[0182] A flow through the tool can be between 50 and 1000 m.sup.3/h. Preferably the flow can be between 1000 and 30 000 m.sup.3/h per square meter of the porous product face of the tool.

[0183] The second product face of the press tool of the first mold may be heated to about 150-500° C., preferably 150-400° C., 200-500° C., 200-400° C., or 200-300° C., and in most cases 240-280° C.

[0184] The porous first product face of the pick-up press tool of the first mold may be heated to about 100-150° C.

[0185] A pressing pressure between the product faces of the pick-up press tool and the press tool may be on the order of about 390-1570 kPa, and in most cases 580-1170 kPa.

[0186] The pressing pressure may be applied during a first pressing time of 0.1-4.0 second, preferably 0.5-2.0 second. In most settings, a pressing time on the order of 0.5-1.5 second is sufficient, and often also 0.5-1 second.

[0187] Typically, in this first step, an initial water content of the pulp slurry layer is 70-90% by weight and after the pressing step has been performed, a final water content may be 45-65% by weight, typically about 50-60% by weight.

[0188] After the first pressing step 102, the pulp slurry layer, now with a substantial amount of its solvent removed, may be transferred 103 to a second press mold. The transfer may be performed by means of a transfer tool, as described above in relation to FIG. 2a-2e. Consequently, at least a portion of the pulp slurry layer may be formed during the transfer.

[0189] During the transfer step, a vacuum may be applied to a rear side of the transferring tool wall, such that the pulp slurry layer is held to the transferring tool wall. In order to release the pulp slurry layer from the transferring tool wall, it is possible to instead apply pressurized air to the rear side of the transferring tool wall.

[0190] Alternatively, or as a supplement, a vaccum may be applied to a rear side of a porous product face of the second mold, causing the pulp slurry layer to be received by the second mold.

[0191] During the transfer, a product face of the transfer tool may be heated to about 100-150° C.

[0192] Consequently, an additional drying effect of the pulp slurry layer can be achieved and/or the pulp slurry layer can maintain a fiber warmth for formability.

[0193] The second mold may comprise a pair of mating press tools, one of which may have a porous product face, which contacts the pulp slurry layer, and through which a vacuum can be drawn.

[0194] The second mold may comprise a first press tool presenting the porous product face, and a second press tool presenting a second product face. The second product face may be porous or non-porous. Alternatively, the second product face may present porous portions and non-porous portions.

[0195] The transfer 103 may be performed by transferring the pulp slurry layer from the first mold to the porous product face of the first press tool of the second mold, by means of the transfer tool.

[0196] In a second pressing step 104, the pulp slurry layer may be pressed in the second mold. The pulp slurry layer may then be pressed against the second product face of the second press tool of the second mold. In this second pressing step 104, a pressure lower than the surrounding ambient pressure is applied at a rear side of the porous product face of the mold, thus resulting in a vacuum at the rear side of the porous product face, causing solvent vapor, such as steam, to be drawn through the tool.

[0197] The porous product face of the second mold may have a porosity of 25-50% with hole sizes 0.1-1.2 mm, preferably 0.25-1.0 mm.

[0198] However, in the second pressing step 104, the pressure applied at the rear side of the porous product face of the second mold may be higher than that provided in the first pressing step 102.

[0199] In particular, the pressure provided in the first pressing step 102 may be 1-99% of that provided in the second pressing step 104, preferably 50-99%, 90-99%, 95-99% or 99-99.9%.

[0200] In the second pressing step, the absolute pressure applied to the rear side of the porous product face of the second mold may be 200-900 mbarA, preferably 300-800 mbarA, but always greater than in the first pressing step.

[0201] A flow through the tool can be between 50 and 1000 m.sup.3/h. Preferably the flow can be between 1000 and 30 000 m.sup.3/h per square meter of the porous product face of the tool.

[0202] At least one of the product faces of the second mold may be heated to about 110-500° C., preferably 110-400° C., 150-500° C., 150-400° C., 200-500° C., 200-400° C., or 200-300° C., and in most cases 240-280° C. Typically, all product faces making up the second mold and contacting the pulp slurry layer may be heated.

[0203] A pressing pressure between the product faces of the first and second press tools of the second mold may be on the order of about 390-1570 kPa, and in most cases 580-1170 kPa.

[0204] The pressing pressure may be applied during a second pressing time of 0.1-4.0 second, preferably 0.5-2.0 second. In most settings, a pressing time on the order of 0.5-1.5 second is sufficient, and often also 0.5-1 second.

[0205] Typically, in this second pressing step, an initial water content of the pulp slurry layer may be about 45-65%, typically about 50-60% by weight.

[0206] A final water content may be about 25-40% by weight, preferably about 30-35% by weight.

[0207] After the second pressing step 104, the pulp slurry layer, now with a substantial amount of its solvent removed, may be transferred 105 to a third press mold. The transfer 106 may be performed in the same manner as the transfer step 103 and with similar equipment. Consequently, at least a portion of the pulp slurry layer may be formed during the transfer.

[0208] Alternatively, the equipment may differ such that the second transfer tool transfer the pulp slurry layer without forming.

[0209] The third press mold may be designed essentially as the second press mold.

[0210] The third mold may comprise a pair of mating press tools, one of which may have a porous product face, which contacts the pulp slurry layer, and through which a vacuum can be drawn.

[0211] The third mold may comprise a first press tool presenting the porous product face, and a second press tool presenting a second product face. The second product face may be porous or non-porous. Alternatively, the second product face may present porous portions and non-porous portions.

[0212] In a third pressing step 106, the pulp slurry layer may be pressed in the third mold. The pulp slurry layer may then be pressed against the second product face of the second press tool of the third mold. In this third pressing step 106, a pressure lower than the surrounding ambient pressure is applied at a rear side of the porous product face, thus resulting in a vacuum at the rear side of the porous product face, causing solvent vapor, such as steam, to be drawn through the tool.

[0213] The porous product face of the third mold may have a porosity of 25-50% with hole sizes 0.1-1.2 mm, preferably 0.25-1.0 mm.

[0214] However, in the third pressing step 106, the pressure applied at the rear side of the porous product face of the third mold may be higher than that provided in the second pressing step 104.

[0215] In particular, the pressure provided in the second pressing step 104 may be 1-99% of that provided in the third pressing step 106, preferably 50-99%, 90-99%, 95-99% or 99-99.9%.

[0216] In the third pressing step, an absolute pressure provided at the rear side of the porous product face of the third mold may be 200-900 mbarA, preferably 300-800 mbarA, but always greater than in the second pressing step.

[0217] A flow through the tool can be between 50 and 1000 m.sup.3/h. Preferably the flow can be between 1000 and 30 000 m.sup.3/h per square meter of the porous product face of the tool.

[0218] At least one of the product faces of the third mold may be heated to about 100-400° C., preferably 100-300° C., 150-400° C., 150-300° C., 200-300° C., or 200-280° C., and in most cases 240-280° C. Typically, all product faces making up the third mold and contacting the pulp slurry layer may be heated.

[0219] A pressing pressure between the product faces of the third mold may be on the order of about 390-1570 kPa, and in most cases 580-1170 kPa.

[0220] The pressing pressure may be applied during a third pressing time of 0.1-4.0 second, preferably 0.5-2.0 second. In most settings, a pressing time on the order of 0.5-1.5 second is sufficient, and often also 0.5-1 second.

[0221] Typically, in this third pressing step, an initial water content of the pulp slurry layer may be about 25-45% or 25-40% by weight, preferably about 30-40% or 30-35% by weight, and a final water content may be less than about 5% by weight, preferably less than about 1% by weight.

[0222] After the third pressing step 106, the pulp slurry layer, now with most of its solvent removed, may be transferred 107 out of the machine.

[0223] Optionally, additional steps, such as surface treatment, cutting or printing may be performed on the thus essentially dry product. The product may then be packaged, stored and shipped.

[0224] It is noted that the third pressing step 106, and thus also its related transfer step 105, is optional. Hence, the process may be finished after the second pressing step 104 with the output step 107 following immediately.

[0225] Thus, in the first pressing step, an initial water content of the pulp slurry layer may be 70-90% by weight and a final water content may be 25-50% by weight, preferably about 30-35% by weight.

[0226] In the second pressing step, an initial water content of the pulp slurry layer may be about 25-50%, preferably about 30-35% by weight, and a final water content may be less than about 5% by weight, preferably less than about 1% by weight.

[0227] Further, the method may comprise at least one optional washing step of the pulp slurry layer. The washing step may be performed after the transfer step 103 and before the second pressing step 104 and/or after the transfer step 105 and before the third pressing step 106.

[0228] Further, the method may comprise at least one step wherein a laminate or a coating is applied to the pulp slurry layer or pulp product. The laminate or coating may be applied between the first and second pressing step, or between the second and third pressing step, or after the third pressing step.

[0229] It is noted that the vacuum sources provided must be dimensioned so as to provide a flow that is sufficient to evacuate the amount of steam generated during the heating/pressing steps, and also to accommodate the liquid water that is drawn out by the vacuum applied to the respective mold.