WO2024194316A1

WO2024194316A1 - Multi-layer material for press molding, a delivery system and a resulting fiber product

Info

Publication number: WO2024194316A1
Application number: PCT/EP2024/057333
Authority: WO
Inventors: Lars Sandberg
Original assignee: Blue Ocean Closures Ab
Priority date: 2023-03-21
Filing date: 2024-03-19
Publication date: 2024-09-26

Abstract

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.

Description

Multi-layer material for press molding, a delivery system and a resulting fiber product

Field of the invention

The present invention relates to relates to a material for press molding of a fiber product, intended to be formed at high pressure and high temperature, preferably by means of a press pad device and a stamp device, wherein said material results in a fiber product. It also relates to an efficient delivery system to such press molding and a resulting product with enhanced mechanical and resistive properties. It also relates to a three-layer material concept for enhanced product and recycling properties. It also relates to a method for recovery.

Background

A fiber product can be made by pressing a web or a sheet of fibers. Typically, a combination of natural fibers (e.g. wood pulp fibers), synthetic fibers (e.g. polyolefin based fibers which may be polyethylene, polypropylene or polyethylene therephtalate) and other additives such as binder or dye. In some applications it is preferred that such a web essentially merely comprises of natural fiber, with or without additives. Typical process conditions are 150 - 250 °C and pressures 100 - 10000 Bar (200 - 2000 Bar). Moisture content may typically be less than 20%. In many applications the material is produced in an integrated operation in line with the pressing operation in order to offer enough forming flexibility through using a material with little internal strength.

Examples of known methods described above are shown in EP 3736099 and W02020/165780. The fiber product can be in the form of a hollow product, for example a package or a closure (lid, screw cap or similar), but can also be a flat product. Products can be formed from a web of the material and punched I cut in connection with forming, e.g. that have been completely or partially separated from the web to allow deeper shaping. This exposure is typically done by cutting the material into a shape that is adapted to the final shape in direct proximity to the forming process. Typically, for example, a roundel is cut to form a round package.

The press molding typically takes place with two tools where both the outer tool (pad) and the inner tool (stamp) can consist of several parts to enable discharge of the finished product. Typically, the pad opens while the stamp collapses. The piston, parts of the piston or parts of the pad can also be made of a compressible material which enables greater vertical compressive forces, typically against the sides of the cavity, by the tool material being reshaped during the compression.

If the material is not produced (or laid) in direct proximity or in line with the stamping and forming process, it needs to have some strength (physical properties) two withstand the operations of for example production, drying, cutting into roll width, winding, unwinding cutting into blanks and the feeding operations. Typically, the material is exposed to tensile forces from line tension and shear forces from cutting and handling.

The material will also need a certain stiffness, predominantly bending stiffness, for example for handling and feeding operations. Specifically, the surface of the material when stored, for example in a roll or on a distribution pallet, risk to interlock or fuse with connecting surfaces causing a material that are hard to separate, dusting when separating or that is damaged when being separated. This is a known problem also with strong materials and referred to as blocking but the problem becomes much bigger with the soft or less defined material typically used in press forming.

Normally fiber materials for 3D pressed or folded packing products are delivered flat in one out of three main ways: on rolls, sheets or blanks. The downside with the existing methods is that rolls have a poor volume efficiency, both from the round shape as such and from the void created by the central unwinding core. For blanks and sheets the volume efficiency can be very high but the nature of this system is that the material is cut into individual items creating additional complication and complexity in the feeding system increasing cost and lowering production efficiency.

When the material is formed into a product, the internal bonds between a number of fibers need to be low or non-existing. This is due to that the material partly shifts shape through that fibers are partly reorganized or at least through that bonds are broken, for example through delamination. Typically, in press forming operations, there is an optimum moisture content of the material, as fiber-based materials typically get weaker when at a higher moisture content. This put extra demand on the original strength and relative wet strength properties of the ingoing material.

The final product will need to have certain minimum strength and resistive properties. These are partly guided by the process parameters such as pressure, temperature and forming time but also from the material constitution and additives. In some applications the strength and resistive properties might need to be higher on the surface on the top and bottom or inside and outside of the product. For example, a packing product will have extra stress on the outside from handling and on the inside from interaction with packed products. For items having some kind of closing mechanism, the stress comes from interaction between the different parts of the opening mechanism, for example interaction between lid and container or between inside and outside threads.

Many of the final products will be submitted to recycling where the fibers are separated to be used in new products. This puts special demand on the product so that only a minimum amount of fibers are bonded in a way so that they cannot be separated in a recycling operation, typically a re-pulping operation. As the re-pulping operation benefits from thinner materials and objects it is an advantage if weaker layers are introduced allowing the object to delaminate and the resulting tougher layers to be better exposed to the re-pulping operation and be separated more efficient.

Thus, there are still need for providing products which are easily recyclable and/or compostable.

Summary of the invention

The present invention solves/alleviates one or more of the problems by providing according to a first aspect a multilayer substrate comprising at least one layer providing tensile strength and one layer containing fibers with an internal strength low enough to be formed in a press forming operations, forming new bonds in, at least partly, new relative positions.

Also, according to a second aspect of the present invention there is provided method for treating a multilayer substrate according to any one of the preceding claims for providing a multilayer product comprising the following steps: a) providing said multilayer substrate, b) subjecting said substrate to high pressure, and c) subjecting said substrate to high temperature, thus providing a multilayer product, optionally involving adding pre-expanded microspheres and/or expandable microspheres preferably adding said microspheres to said multilayer substrate before providing said multilayer substrate in step a) or providing said microspheres simultaneously with step a), most preferred adding said microspheres to said multilayer substrate before providing said multilayer substrate in step a).

Also, according to a third aspect of the present invention there is provided a multilayer product obtainable by a method according to the second aspect.

Also, according to a fourth aspect of the present invention there is provided use of a multilayer product according to the third aspect wherein said product is/are a part(s) of a moulded product, such as a lid, a screw cap, a container, a bread clip or a package, wherein said container may be 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, such as a folding boxboard.

Also, according to a fifth aspect of the present invention there is provided a method for recycling a multilayer product according to the third aspect for providing re-cycled pulp comprising the following steps: i) providing said mulitlayer product, preferably after usage thereof, ii) submerging said product into a liquid, preferably water, most preferred warm water, 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.

Detailed description of the invention

The expressions “fibre” or “fiber” may be used interchangeably in the present specification and would have the same meaning. The expressions “mold” or “mould” may also be used interchangeably in the present specification and would have the same meaning.

According to a preferred embodiment of the first aspect said multilayer substrate comprises at least one layer with pre-expanded microspheres and/or expandable microspheres.

According to a preferred embodiment of the first aspect said multilayer substrate comprises at least one layer with a fiber mat produced though airlaid technology and/or a fiber mat produced through wetlaid technology

According to a preferred embodiment of the first aspect said multilayer substrate comprises at least one layer with a paper sheet, wherein preferably said sheet has a moist content of from about 4 to about 25%, most preferred from about 7 to about 15 %..

According to a preferred embodiment of the first aspect said expandable microspheres are thermally expandable thermoplastic microspheres or pre-expanded thermally expandable thermoplastic microspheres, or a combination thereof. The expandable thermoplastic microspheres can be of fossil based or bio-based polymer material. Examples of such expandable microspheres are microspheres marketed under the name Expancel Microspheres by Nouryon.

According to a preferred embodiment of the first aspect said layer providing tensile strength provides a tensile strength that is at least about 10 %, preferably at least about 20%, most preferred at least about 50 %, higher than the tensile strength of the other layer.

According to a preferred embodiment of the first aspect said substrate is at least a three- layer material. Said substrate may further have more layers than three, such as four, five, six, seven, eight, nine or ten layers. Preferably at least one of the layers of said at least three- layermaterial comprises at least one fossil based and/or biobased polymer and/or biodegradable polymer such as PET (polyethylene therephtalate) or one or more polyolefins, and wherein the bio-degradable polymer, is selected from the group comprising PLA (polylactic acid), PHBH (Poly (3- hydroxy butyrate- co-3- hydroxyhexanoate) PHA (poly-hyaluronic acid) and PEF (polyethylene fuaronate) or a combination thereof.

Non-limiting examples of polyolefins are polyethylene (PE) and polypropylene (PP). Said polymers may be added in pellet form before pressing or in the form of a solid foil (before or after pressing) that will face the content of the container when using the at least a three-layer material in a food context, such as in a cap for milk or other dairy products. If using a foil there will be a laminate and accordingly said polymer will face the food product. Said polyethylene may preferably be bio-based. Said polymer material may further enhance the stiffness of the at least three-layer material. A PET/PE bicomponent may further be used. Also, a binder such as EVA, latex or starch may be present additionally. Also Lyocell may be used in the above context.

According to a preferred embodiment of the first aspect said higher tensile strength is provided by at least one of the outer layers, preferably wherein the minimum tensile strength is about 75 N/m (CD). CD=Cross-machine direction According to a preferred embodiment of the first aspect said higher tensile strength is provided by the two outer layers, preferably wherein the total minimum tensile strength is about 150 N/m (MD). Thus, said layers provide for about 75 N/m, whereas the middle layer provides with an essentially minor part. MD=Machine direction

According to a preferred embodiment of the first aspect the layer(s) with higher tensile strength is thinner than the central layer(s).

According to a preferred embodiment of the first aspect the material with low initial tensile strength provides one or more layer(s) with better re-pulpability.

According to a preferred embodiment of the first aspect, at least one of the outer layers has a higher hydrophobicity and/or oleophobicity, preferably by using a water and/or grease repellent, such as AKD (alkyl ketene dimer), ASA (alkenyl succinic anhydride) or waxes or latex or rosin or biobased fibres or cellulose acetate or a combination thereof. This may be achieved for said at least one of the outer layers, or both, as follows:

In the method, a bulky cellulosic material (which may have a specific volume of from about 7 to about 8 cm³/g) is pressed after going through a decurler unit, whereby a water and/or grease repellent is applied before pressing (using e.g. spraying). Said cellulosic material may be wetlaidor air-laid. The combination of pressure (from about 10 to about 100MPa, preferably from about 20 to about 30 MPa) and heat (from about 120 to about 250°C, preferably from about 120 to about 180°C) is applied to the material for 0.5 - 2 s and this yields a high-density cellulose object (from about 1.11 to about 1.25 kg/dm³) with a relatively limited porosity and a relatively capillary-free structure. This process affects the material in several ways: a) the high temperature at which the material is pressed allows to heat the fibre mat above the melting point of the agent used for water / grease repellency. This allows the agent to redistribute I spread more evenly on I around the fibres during pressing and reach a more homogeneous fibre coverage, and therefore a higher hydrophobicity and/or oleophobicity. b) The extremely high densification of the material during pressing yields a smooth, closed surface object with low specific volume when compared to other cellulosic materials such as paperboard or wet moulded cellulose. The densification of the fibre network allows for the creation of a network of hydrophobic and I or oleophobic agent (i.e. water and/or grease repellent) around the fibres that is then locked in the structure due to the lack of available space to flow. Moreover, the smooth, closed surface further reduces the flowing possibility and locks the agent in the material, as well as decrease the possibility of hydrolysis, therefore increasing the performance. Finally, the densification of the material increases the volume fraction of hydrophobic and I or oleophobic agent (i.e. water and/or grease repellent) in a given amount of material, leading to a further densification of the network and increase in performance.

Decurler-units that may be used in connection with the above-mentioned method may be e.g. a roll-decurl component provided by Maxson Automatic Machinery Company or a decurl unit provided by Ricoh. Said decurl unit may comprise one sponge roller, two metal rollers and two paths for paper or other cellulosic material. The decurl strength and curl direction may be adjusted. There may be a “sandwich” configuration wherein there is an upper pressure roller, a decurl roller and a lower pressure roller. The de-curler (or de-curler unit) has a mechanical effect on the fibers, which means that any bending present on said fibers initially, may essentially be removed using the de-curler.

The above-mentioned method may also be expressed as follows:

Said method for enhancing the water and/or grease repellency in a material, suitable for packaging purposes, comprises the following steps: a) providing a material, preferably containing cellulosic fibres, b) passing said material through a decurler unit, c) spraying a water and/or grease repellent on said treated material, d) subjecting said repellent treated material to high pressure and to high temperature, thus providing a product with enhanced water and/or grease repellency, useful e.g. in packaging solutions for food or beverages.

In said method preferably the high pressure and high temperature of step d) is provided by a press pad device and a stamp device. Most preferred the high pressure and high temperature of step d) is a combination of a pressure of from about 10 to about 100 MPa, preferably from about 20 to about 60 MPa, most preferred from about 30 to about 60 MPa, and a temperature of from about 80 to about 250 °C, preferably a temperature of from about 120 to about 250 °C, most preferred from about 120 to about 180 °C, whereby preferably said conditions is upheld during a time period of from about 0.5 to about 2 s. In said method the material emanates from ChemiThermo Mechanical Pulp, Thermo Mechanical Pulp, Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof. The material may also emanate from bleached or non-bleached pulp, or a combination thereof. The material may emanate from hardwood or softwood, bagasse, algae or straw or other annual plants or a combination thereof.

In said method preferably the material provided in step a) is an air-laid material, preferably containing cellulosic fibers, or a wetlaid material, preferably containing cellulosic fibers, or a combination thereof, wherein preferably said material provided in step a) has a specific volume of from about 7 to about 8 cm³/g.

As said above, said water and/or grease repellent is one or more sizing agents, preferably selected from the group comprising alkylketendimer (AKD), alkenyl succinic anhydride and waxes or a combination thereof.

The method set out above may e.g. provide a product with the following characteristics: A material, preferably containing cellulosic fibers, with enhanced water and/or grease repellency, suitable for packaging purposes, having a density from about 1.11 to about 1.25 kg/dm³, wherein preferably said enhanced repellency is achieved using one or more water and/or grease repellents, preferably one or more sizing agents.

Said product with enhanced the water and/or grease repellency, may be obtained by a method as set out above.

Said product with enhanced water and/or grease repellency as said above may be part of a moulded product, such as a screw cap, a container, a bread clip or a package, wherein said container may be 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, such as a folding boxboard.

Said product with enhanced water and/or grease repellency may be used in a multi-layered, such as three-layered, moulded product, such as a screw cap, a container, a bread clip or a package, wherein said container may b e 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, such as a folding boxboard, wherein preferably the layer with enhanced water and/or grease repellency is facing the food or beverage during the final usage of the consumer. Said multilayer product may also be provided so that one of the outer layers form threads or click-on function for sealable packaging, for example a container, a closure or a part of container or closure.

As set out above, hydrophobicity may be achieved by using e.g. AKD and/or waxes and/or biobased fibres and/or lignin. Also, products using click chemistry may achieve hydrophobicity on their own or in combination of a binder. Sol-gel treatments may also be used to achieve a water repellency effect of the pressed material. An example of AKD is shortened AP. An example of wax is shortened AS or ASCL when combined with a binder.

According to a preferred embodiment of the first aspect at least one of the outer layers has a higher relative wet strength.

According to a preferred embodiment of the first aspect at least one of the outer layers has a higher density.

According to a preferred embodiment of the first aspect the density is below about 0.5 kg/dm³, preferably from about 0.1 to about 0.4 kg/dm³.

According to a preferred embodiment of the first aspect the grammage is from about 100 to about 2000 g/m², preferably from about 300 to about 1500 g/m². If tissue paper is used as a starting material for one layer, preferably an outer layer, it may have a grammage of from about 15 to about 18 g/m², preferably about 16.5 g/m².

According to a preferred embodiment of the first aspect the moisture content is from about 4 to about 25%, preferably from about 7 to about 15 %.

According to a preferred embodiment of the first aspect at least one of the outer layers comprises one or more additives for extra strength and wet strength, preferably wherein at least one component of said additive(s) comprises fibers of man-made polymers.

The substrate mentioned above for the embodiments of the first aspect may emanate from CTMP (ChemiThermo Mechanical Pulp), TMP (Thermo Mechanical Pulp), Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, pulp for board or carton, or a combination thereof. Further, said substrate may emanate from bleached or nonbleached pulp, or a combination thereof. Additionally, said substrate may emanate from hardwood or softwood, bagasse or straw or a combination thereof.

According to a preferred embodiment of the second aspect said method also involves the following steps when at least one layer comprises pre-expanded microspheres and/or expandable microspheres: d) providing said multilayer substrate into a mold assembly and heating said material from about 50 to about 150° C, preferably from about 60 to about 120° C, most preferred from about 80 to about 100° C, thus providing a dry content of about 50 to about 70% and thus providing an expanded or foamed multilayer product.

According to a preferred embodiment of the second aspect steam is applied during said step d) for expanding said multilayer substrate.

According to a preferred embodiment of the second aspect the high pressure and high temperature of step b and/or c) is provided by a press pad device and a stamp device.

According to a preferred embodiment of the second aspect the substrate emanates from

CTMP (ChemiThermo Mechanical Pulp), TMP (Thermo Mechanical Pulp), Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof.

According to a preferred embodiment of the second aspect the substrate emanates from bleached or non-bleached pulp, or a combination thereof.

According to a preferred embodiment of the second aspect the substrate emanates from hardwood or softwood, bagasse, algae or straw or a combination thereof.

According to a preferred embodiment of the second aspect the step a) is preceded by a delivery step comprising forming the substrate into a strip and subsequently folding said strip.

According to a preferred embodiment of the third aspect the multilayer product according to the third aspect is a moulded product, such as a screw cap, a container a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or autoclave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard.

According to a preferred embodiment of the third aspect the multilayer product is provided so that one of the outer layers form threads or click-on function for sealable packaging, for example a container, a closure or a part of container or closure.

Thanks to the present invention a material that can be used in press forming operations, where fibers can be partly separated and re-attached, can be produced to have a higher tensile, share and surface strength and be feed into the forming operation in an efficient way. In addition, outer layer and surface properties of a formed product can be strong and resistant enough at the same time as the amounts of strengths agents are minimized and high re-pulpability and therefore high recyclability is maintained.

In one application of the invention the multi-layer materials are folded in or prior to the pressing and forming operations, thereby creating internal structures of stronger material where the outer layers interact. In this way a structure may be locally reinforced while minimizing use of strength additives and withholding recyclability.

The novel material in this invention allows through its tensile strength and handling properties for new delivery systems where the material can be delivered in a strip folded on a pallet. This has two distinct advantages to production of items, specifically high-volume packaging items. The delivery method is made possible through using the strong but soft material resulting from the multi-layer structure where the strength and possibility to fold without creating creases that influence the final product, allows for a system with high volume efficiency. As the folding are creating a block of a continues material it combines the volume efficiency of sheets on a pallet with the production advantage with a continually feed material as from a roll.

The moisture content (set out for certain embodiments above) is an advantage during the press forming (c.f. the second aspect of the present invention). Preferably said moisture is added before the pressing of the substrate (i.e. raw material) is achieved.

An important function in caps, lids or similar constructions made of fiber is compressability and shape stability. Through adding pre-expanded microspheres and/or expandable microspheres to the network of fibres the ability of the material after compression to bring back its shape, the so-called bounce back ability is increased. This can also be expressed so that the viscoelastic characteristics of the material can be influenced so that the tendency for time dependent deformation, so called ’’creep deformation” is decreased. The closed spheres may be added to e.g. paper sheet (material) in different ways. Pre-expanded microspheres and/or expandable microspheres may be added.

Said microspheres may be added during different stages of the manufacturing process. They may be added before the manufacturing of the fiber mat, but preferably they are added in connection with the manufacturing of the fiber mat. This may be done during dry or wet laying of the fiber mat. Microspheres may also be added in direct connection with the form pressing of the fiber mat. In case the product is to be used in the form of a closing member or sealing member in a container, extra fiber is added after the form pressing. Said material may be fiber material, preferably cellulosic, a polymeric material or a combination of these.

Microspheres may be added in expanded or in non-expanded form, or in a combination of both. The non-expanded spheres may fully or partly be expanded through heating in the manufacturing process of the fiber mat (wet or dry). The spheres may also be expanded through the heat that is conveyed to the pressing operation, alternatively, when a closed container before or directly in the filling or closing process (c.f. dairy operations when milk products are filled into containers, essentially made from cellulosic fibers, which subsequently are sealed).

The final products may then contain fully or partly expanded microspheres, alternatively spheres, which have been expanded and then compressed in the pressing operation.

Preferred features of each aspect of the invention are as for each of the other aspects mutatis mutandis. The prior art document (s) mentioned herein are incorporated to the fullest extent permitted by law. The invention is further described in the following example, together with the appended figures, which do not limit the scope of the invention in any way.

Embodiments of the present invention are described as mentioned in more detail with the aid of example of embodiments, together with the appended figures, the only purpose of which is to illustrate the invention and are in no way intended to limit its extent.

Figures Fig. 1 shows a schematic production of a multi-layer material according to the present invention where, typically one or both of the outer formed layers, are strong and carry the loose held together other layers.

Fig. 2 shows a schematic slitting operation where a bigger roll of the internally loose held together material is re-winded and slitted to several smaller rolls adopted thereby exposed to high tensile tension in the web and share forces from the slitting operations.

Fig. 3 shows a schematic forming operation where the partly loose held together fiber material are un-winded, cut, pulled, draped pressed and possible post cut into a multilayer structure with extra strong inside and/or outside surfaces.

Fig. 4 shows a schematic multilayer formed structure where one or both of the outer layers has a higher resistance towards the re-pulping operations while the central layer is more easily separated and through that delaminating the structure increasing re-pulpability and through that recyclability.

Fig. 5 to 7 show pressing when making closure suitable for use on a bottle

Fig. 8 - 9 show hydrophobicity for lids

Fig. 10 shows hydrophobicity for closures

Fig. 11 shows closures for usage on cosmetics containers

Fig. 12 shows laminated closure and hydrophobicity emanating therefrom.

Fig. 13 reflecting a further trial whereby a coffee lid was made

Examples

1. Exemplary description

A. Forming of a first outer or inner layer B. Forming of a second central layer

C. Forming of a third layer outer or inner layer

D. Additional manufacturing processes where the material is exposed to mechanical or chemical stress. Mechanical stress is typically enforced through compression (calendering) and tensile stress in mechanical or drying operations. Chemical stress are typically enforced trough moisture or water for example from an operation adding a water solvable or dispersible additive.

E. Winding operation where the material is exposed to tensile forces in order to create a stable enough roll. If the tension in the winding operation are not high enough the tension inside the roll will not be sufficient to prevent so called telescoping in handling.

F. Rewinding operation where the web tension is needed to pull the material from the larger original roll and high enough to create sufficient web tension in the smaller resulting roll in order to enable safe handling. The tension is typically achieved through that the smaller roll is driven and that the rotation of the bigger roll is held back or braked.

G. Unwinding in the converting operation. The web tension creating tensile forces of the material is needed to create a flat and controlled web. This is typically achieved through that the material is pulled by a feeding unit and that the roll is held back through a braking mechanism. Unwinding means that the layers of the roll where the inside material rests towards the outside of the material needs to be separated creating tensile forces but also out of plane or share forces risking the material to break, dust or that part of once surface resides on the other if the surface strength of the material is not high enough.

H. In some operations the material is cut into blanks prior to the feeding operation creating tensile and shear forces on the material.

I. The material, as a web or as sheets (or blanks) are typically fed into the pressing operation (J.) through a pushing operation by the feeder in order to avoid tensile forces then the material later is punched or draped into the mould (see Fig 1 and 2 “press pad device”). The pushing operation create compressive and buckling forces on the material demanding that the material is strong and stiff enough not to be compressed, folded or buckled when fed.

J. Pressing device (reference also to figs 1 and 2 below). The material is typically pushed flat into the pressing area and then pushed or draped into the press pad device with the stamp or with a dedicated tool. The material needs to be strong enough not to break from tensile or shear forces crated from the pressing device and the walls of the pad and the same times a significant amount of fibers need to be loose enough to be relocated under the pressing operation. During the pressing operation the material will be formed and with new bonds formed. The nature of the material and the additives added will determine the properties of the new laminate structure. Typically, materials will contain strength, wet-strength and hydrophobic properties and may be stronger and/or more resistant to water while materials without these additives will create properties enabling better re-pulping properties. Where the material is folded in the pushing down or draping operation it will for folds where the inside or outside material will come in direct contact with itself forming, typically stronger, re-enforcement structures.

K. The forming and pressing operation results in a multilayer structure typically with the outer and/or inner layers are given extra strength from the additives originally added to create a or several strong layers in the manufacturing and converting operations. If the item formed is to be cut after forming, the strength of outer(s) aid the cutting operation through better shear and bending resistance.

The formed product would benefit from extra strength.

As a non-limiting example, the minimum tensile strength could be 150 N/m (MD) in total, where there would be essentially no strength in the middle layer. Thus, in each outer layer there would be a tensile strength of about 75 N/m (CD).

L. After use the fibers in the item need to be recycled to enable new use as packaging or other products. This is typically done trough that the item is collected, transported and, together with other fiber and paper products re-pulped. The re-pulping, which constitutes the fifth aspect of the present invention, is typically done in an operation where the items are submerged into warm water, with or without decoupling, agents and exposed to shear forces causing fibers bonds to separate. Typically, stronger bonds, bonds that are aided with additives and thick structures are harder to re-pulp.

M. The multilayer where one or several layers are easier will delaminate or partly delaminate causing the easier to re-pulp layers to separate into single fibers. The harder to separate layers will end up as thinner layers or flakes and through that geometrical transformation they separate to single fibers easier than if they were kept in a thicker structure. If all or part of the stronger layer would not separate totally these will be screened of enabling the major part of the structure to be recycled into new paper or fiber products. 2. Measurements

If air-laid trial material (carrier sheet), that is a multi-layered material according to the present invention, has been treated during a trial and is subsequently measured with regard to e.g. tensile strength conducted on the full material (including tissue), data (testing results) can be collected and may be represented as follows:

Elongation and air permeability of the tissue carrier are two important parameters for converting on the air-laid machine.

Additional measurements on an exemplary thermobonded air-laid, tissue carrier, gave the following values:

Property Value/Unit Test method

Basis weight 700 g/m² NWSP 130.1. R0 (15)

Thickness (2,0 kPa) 5.6mm NWSP 120.6.R0 (15)

Density 0.13g/cm³ Calculated

Tensile strength (dry) MD 49 N/50mm NWSP 110.4. R0 (15)

Tensile strength (dry) CD 46 N/50mm NWSP 110.4. R0 (15)

Elongation (dry) MD 1.02 % NWSP 110.4. R0 (15)

Elongation (dry) CD 1.31 % NWSP 110.4. R0 (15) Bond Strength 0.2 N/50mm

3. Trials with hydrophobic materials

Material treated with various hydrophobic products were manufactured and pressed into lids or screw caps.

The materials were one or two sides treated with AKD (AP), wax dispersion (AN), or click chemistry products with (ASCL) and without (AS) additional binder. Percentages (dry/dry) of added hydrophobic product were either 1% or 2%. Layers of materials were superposed before pressing in order to create multilayer materials with varying levels of hydrophobic treatment in and outside. The materials were pressed between 80-140°C using a servo press and screw caps or lid tools depending on the desired geometry.

The following table summarises the material assemblies that were evaluated. The number (0, 1 , 2) represents the percentage of hydrophobic treatment in each layer.

All materials performed well both in terms of formation of the 3D object and water repellency. Variations in mechanical performances were observed depending on type and amount of treatment, which may allow to modulate the performances of the final product according to need and specifications.

Pressing is highlighted in Figures 5 - 7. In figures 8 and 9 it is clearly to be seen the results after hydrophobic treatment as set out above useful as lids. The closure seen in figure 10, was made in a form suitable for usage on a bottle, such as a bottle useful for alcoholic beverage.

4. Trials with materials comprising various types of polymer fibres

Multilayer materials were produced with all layers containing between 5-10% (dry/dry) of reinforcement polymer fibres. Fibres used were of the PHA, PHBH, Cellulose acetate, PLA, and PE/PET families. The bulky materials were pressed into screw caps at 140°C using a servo press equipped with the corresponding tool. All materials yielded fully formed closures with high stiffness, with PLA and PHA fibres in particular leading to well formed and stiff 3D objects, indicating a strong potential use of these sustainable polymer fibres as mechanical reinforcement in the pressed fibre material

5. Lamination of biopolymer film

Polymer films between 20-150pm thickness were placed on top of the bulky cellulosic multilayer material before pressing between 100-140°C in a servo-press using a screw cap tool. The resulting pressed 3D object comprises a densified cellulosic part laminated without the use of glue with a polymer film that provides barrier performances such as hydrophobicity, oleophobicity, gas barrier, aroma barrier, etc. depending on the intrinsic performance of the polymer films. Tested films comprise PHA, PLA, and PE films, all yielding objects pressed and laminated in a single operation with said film on either or both sides of the object (see figure 11).

6. Further trials using airlaid

Additional trials with a multilayer made by sandwiching an untreated 700gsm layer between 2 layers of hydrophobic treated material as set out above (i.e. 250+700+250gsm) were carried out. This multilayer material combined the high stiffness, high density of an untreated core cellulosic material with the water repellency properties of the outer treated materials, and may be a way to modulate both the mechanical and water repellency properties of the pressed object (see figure 13 - coffee lid).

Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations that would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted layered configurations or methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.

Claims

1. A multilayer substrate comprising at least one layer providing tensile strength and one layer containing fibers with an internal strength low enough to be formed in a press forming operations, forming new bonds in, at least partly, new relative positions.

2. A multilayer substrate according to claim 1 wherein at least one layer comprises preexpanded microspheres and/or expandable microspheres.

3. A multilayer substrate according to claim 1 wherein at least one layer comprises a fiber mat produced though airlaid technology and/or a fiber mat produced through wetlaid technology

4. A multilayer substrate according to claim 1 wherein at least one layer comprises a paper sheet, wherein preferably said sheet has a moist content of from about 4 to about 25%, most preferred from about 7 to about 15 %..

5. A multilayer substrate according to claim 1 wherein said layer providing tensile strength provides a tensile strength that is at least about 10 %, preferably at least about 20%, most preferred at least about 50 %, higher than the tensile strength of the other layer.

6. A multilayer substrate according to claim 1 , wherein said substrate is at least a three- layermaterial.

7. A multilayer substrate according to claim 6, wherein at least one of the layers of said at least three-layermaterial comprises at least one fossil based and/or biobased polymer and/or biodegradable polymer such as PET or one or more polyolefins, and wherein the biodegradable polymer, is selected from the group comprising PLA, PHBH, PHA and PEF or a combination thereof.

8. A multilayer substrate according to claim 6, wherein said higher tensile strength is provided by at least one of the outer layers, preferably wherein the minimum tensile strength is about 75 N/m (CD).

9. A multilayer substrate according to claim 6, wherein said higher tensile strength is provided by the two outer layers, preferably wherein the total minimum tensile strength is about 150 N/m (MD).

10. A multilayer substrate according to claim 6, wherein the layer(s) with higher tensile strength is thinner than the central layer(s).

11. A multilayer substrate according to claim 1 , 5 or 6, wherein the material with low initial tensile strength provides one or more layers with better re-pulpability.

12. A multilayer substrate according to claim 6, wherein at least one of the outer layers has a higher hydrophobicity and/or oleophobicity, preferably by using a water and/or grease repellent, such as alkyl ketene dimer, alkenyl succinic anhydride or waxes or latex or rosin or biobased fibres or cellulose acetate or a combination thereof.

13. A multilayer substrate according to claim 6, wherein at least one of the outer layers has a higher relative wet strength.

14. A multilayer substrate according to claim 6, wherein at least one of the outer layers has a higher density.

15. A multilayer substrate according to claim 1, 5 or 6 wherein the density is below about 0.5 kg/dm³, preferably from about 0.1 to about 0.4 kg/dm³.

16. A multilayer substrate according to claim 1, 5 or 6 wherein the grammage is from about 100 to about 2000 g/m², preferably from about 300 to about 1500 g/m².

17. A multilayer substrate according to claim 1, 5 or 6 wherein the moisture content is from about 4 to about 25%, preferably from about 7 to about 15 %.

18. A multilayer substrate according to claim 6, wherein at least one of the outer layers comprises one or more additives for extra strength and wet strength, preferably wherein at least one component of said additive(s) comprises fibers of man-made polymers.

19. A method for treating a multilayer substrate according to any one of the preceding claims for providing a multilayer product comprising the following steps: a) providing said multilayer substrate, b) subjecting said substrate to high pressure, and c) subjecting said substrate to high temperature, thus providing a multilayer product, optionally involving adding pre-expanded microspheres and/or expandable microspheres preferably adding said microspheres to said multilayer substrate before providing said multilayer substrate in step a) or providing said microspheres simultaneously with step a), most preferred adding said microspheres to said multilayer substrate before providing said multilayer substrate in step a).

20. A method according to claim 19 comprising the following steps when at least one layer comprises pre-expanded microspheres and/or expandable microspheres:. d) providing said multilayer substrate into a mold assembly and heating said material from about 50 to about 150° C, preferably from about 50 to about 120° C, most preferred from about 60 to about 100° C, thus providing a dry content of about 50 to about 70% and thus providing an expanded or foamed multilayer product.

21. A method according to claim 19 wherein steam is applied during said step d) for expanding said multilayer substrate.

22. A method according to claim 19 wherein the high pressure and high temperature of step b and/or c) is provided by a press pad device and a stamp device.

23. A method according to claim 19 wherein the substrate emanates from ChemiThermo Mechanical Pulp, Thermo Mechanical Pulp, Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof.

24. A method according to claim 19 wherein the substrate emanates from bleached or non-bleached pulp, or a combination thereof.

25. A method according to claim 19 wherein the substrate emanates from hardwood or softwood, bagasse, algae or straw or a combination thereof.

26. A method according to claim 19 wherein step a) is preceded by a delivery step comprising forming the substrate into a strip and subsequently folding said strip.

27. A multilayer product obtainable by a method according to any one of claims 19 - 26.

28. A multilayer product according to claim 27 wherein said product is a moulded product, such as a lid, a screw cap, a container, a bread clip or a package, wherein said container may be 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, such as a folding boxboard.

29. A multilayer product according to claim 27 wherein said product is provided so that one of the outer layers form threads or click-on function for sealable packaging, for example a container, a closure or a part of container or closure.

30. Use of a multilayer product according to claim 27 wherein said product is/are a part(s) of a moulded product, such as a lid, a screw cap, a container, a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or autoclave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard.

31. Method for re-cycling a multilayer product according to any one of claims 26 to 28 for providing re-cycled pulp comprising the following steps: i) providing said mulitlayer product, preferably after usage thereof, ii) submerging said product into a liquid, preferably water, most preferred warm water, 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.