Multi-layer material for press molding, a delivery system and a resulting fiber product
The present invention relates to a multi-layer material for press molding, a delivery system and a resulting fiber product. Also, a method for recovery is disclosed.
1 . A multilayer substrate comprising at least one layer providing tensile strength and at least one layer containing fibers with an internal strength sufficiently low to permit fiber relocation in a press forming operation, forming new bonds in, at least partly, different positions than prior to the press forming operation,
wherein said substrate comprises at least three layers, including at least one central layer positioned between two outer layers, said at least one central layer comprising said at least one layer containing fibers with an internal strength sufficiently low to permit fiber relocation in a press forming operation, forming new bonds in, at least partly, different positions than prior to the press forming operation; and
wherein at least one outer layer has a higher tensile strength and is thinner than the at least one central layer.
2 . The multilayer substrate according to claim 1 wherein said at least one outer layer having a higher tensile strength provides a tensile strength that is at least about 10% higher than the tensile strength of the at least one central layer.
3 . The multilayer substrate according to claim 1 , wherein at least one of the outer layers provides the tensile strength and has a minimum tensile strength of about 75 N/m in a cross-machine direction.
4 . The multilayer substrate according to claim 1 , wherein the two outer layers provide the tensile strength and have a total minimum tensile strength of about 150 N/m in a machine direction.
5 . The multilayer substrate according to claim 1 , wherein the at least one central layer has a low initial tensile strength and a higher re-pulpability than the outer layers.
6 . The multilayer substrate according to claim 1 , wherein at least one of the outer layers has a higher hydrophobicity and/or oleophobicity than the at least one central layer.
7 . The multilayer substrate according to claim 1 , wherein at least one of the outer layers has a higher relative wet strength than the at least one central layer.
8 . The multilayer substrate according to claim 1 , wherein at least one of the outer layers has a higher density than the at least one central layer.
9 . The multilayer substrate according to claim 1 , wherein the multilayer substrate has a density below about 0.5 kg/dm 3 .
10 . The multilayer substrate according to claim 1 , wherein the multilayer substrate has a grammage from about 100 to about 2000 g/m 2 .
11 . The multilayer substrate according to claim 1 , wherein the multilayer substrate has a moisture content from about 4 to about 25%.
12 . The multilayer substrate according to claim 1 , wherein at least one of the outer layers comprises one or more additives for extra strength and wet strength.
13 . A method for treating a multilayer substrate according to claim 1 for providing a multilayer product comprising the following steps:
a) providing said multilayer substrate,
b) subjecting said multilayer substrate to high pressure, and
c) subjecting said multilayer substrate to high temperature, thus providing a multilayer product.
14 . The method according to claim 13 wherein the high pressure and high temperature of step b and/or c) is provided by a press pad device and a stamp device.
15 . The method according to claim 13 wherein the multilayer substrate emanates from chemi-thermomechanical pulp, thermomechanical pulp, chemically pulped wood pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof.
16 . The method according to claim 13 wherein the multilayer substrate emanates from bleached or non-bleached pulp, or a combination thereof.
17 . The method according to claim 13 wherein the multilayer substrate emanates from hardwood or softwood, bagasse, algae or straw or a combination thereof.
18 . The method according to claim 13 wherein step a) is preceded by a delivery step comprising forming the multilayer substrate into a strip and subsequently folding said strip.
19 . A multilayer product obtainable obtained by a method according to claim 13 .
20 . The multilayer product according to claim 19 wherein said product is a moulded product selected from the group consisting of a screw cap, a container, a bread clip, and a package, wherein said container is a disposable drinking cup or dairy product carton or auto-clave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, wherein the paperboard is a folding boxboard.
21 . The multilayer product according to claim 19 wherein said product is provided so that one of the outer layers forms threads or a click-on function for sealable packaging.
22 . Use of a multilayer product according to claim 19 wherein said product is used as a part of a moulded product selected from the group consisting of a screw cap, a container, a bread clip, and a package, wherein said container is a disposable drinking cup or dairy product carton or auto-clave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, wherein the paperboard is a folding boxboard.
23 . Method for re-cycling a multilayer product according to claim 19 for providing re-cycled pulp comprising the following steps:
i) providing said multilayer product,
ii) submerging said product into a liquid,
iii) optionally adding to said liquid one or more decoupling agents,
iv) exposing said product in said liquid for shear forces thus providing a re-cycled pulp.