Multi-layer materials for press molding, delivery systems, and resulting textile products

Abstract

The present invention relates to a multi-layer material for press molding, a delivery system, and the resulting textile product. A recovery method is also disclosed.

Description

[Technical field]

[0001] The present invention relates to a material for pressing textile products intended to be formed at high pressure and high temperature, preferably using press pad and stamp devices, which material gives rise to textile products. The present invention also relates to an efficient delivery system for such pressing and the resulting products with improved mechanical and resistance properties. The present invention also relates to a three-layer material concept for improving product properties and recycling properties. The present invention also relates to a recovery method. [Background technology]

[0002] Textile products can be made by pressing a web or sheet of fibers. Usually, a combination of natural fibers (e.g., wood pulp fibers), synthetic fibers (e.g., polyolefin-based fibers, which may be polyethylene or polypropylene), and other additives such as binders or dyes are conceivable. In some applications, it is preferred that such webs essentially only comprise natural fibers, with or without additives. Typical processing conditions are 150-250°C and pressures of 100-10,000 bar (200-2000 bar). The moisture content may usually be less than 20%. In many applications, the material is produced in an integrated operation together with the pressing operation to provide sufficient molding flexibility by using materials with little internal strength. Examples of known methods described above are shown in EP 3736099 and WO 2020 / 165780. The textile product may be in the form of a hollow product, for example a package or a closure (lid, screw cap, etc.), but may also be a flat product. The product can be formed from a web of material and punched / cut in conjunction with the forming. For example, it can be completely or partially separated from the web to allow for deeper forming. This exposure is usually done by cutting the material into a shape that accommodates the final shape very close to the forming process. Typically, for example, a circle is cut to form a circular package.

[0003] Press molding is usually performed with two tools, both the outer tool (pad) and the inner tool (stamp) can consist of several parts that allow the ejection of the finished product. Usually 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 allows a larger vertical compression force on the sides of the cavity, usually due to the tool material taking shape during compression.

[0004] If the material is not produced (or laid) in close proximity to or in the same line as the stamping and forming processes, it needs to have a certain strength (physical properties) to withstand the operations of e.g. production, drying, cutting to roll width, winding, rewinding, cutting to blanks, and feeding operations. Usually the material is exposed to tension from line tension and shear forces from cutting and handling. The material will also need a certain stiffness, mainly bending stiffness, e.g. for handling and feeding operations. In particular, the surfaces of the material, when stored, e.g. in rolls or on a shipping pallet, run the risk of interlocking or fusing with contacting surfaces, so that the material becomes difficult to separate, creates dust when separating, or is damaged when separated. This is also a known problem for high strength materials, called blocking, but the problem is much greater for soft or poorly defined materials, usually used in press forming.

[0005] Typically, fibrous materials for 3D pressed or folded packaging products are delivered flat in one of three main ways: rolls, sheets, or blanks. Drawbacks to existing methods include poor volumetric efficiency of the rolls, both from the circular shape of the roll itself and from the void created by the central unwinding core. While volumetric efficiency can be very high for blanks and sheets, the nature of the system means that the material is cut into individual items, further increasing the difficulty of the feeding system, increasing complexity, cost, and reducing production efficiency.

[0006] When the material is formed into a product, the internal bonds between some of the fibers must be low or non-existent, since the fibers will be partially rearranged or at least the shape of the material will be partially changed by breaking the bonds, for example by peeling. Usually, there is an optimum moisture content for the material in the press forming operation. Usually, fiber-based materials can be weaker at higher moisture contents. This puts special demands on the original strength and relative wet strength of the incoming material.

[0007] The final product must have certain minimum strength and resistance properties. These are driven in part by processing parameters such as pressure, temperature, molding time, etc., but also by material composition and additives. In some applications, strength and resistance properties may need to be high on the surface, on the top and bottom of the product, or on the inside and outside of the product. For example, packaged products are subject to extra stress on the outside from handling, and also on the inside from interactions with packaged products. For items with some type of closure mechanism, stresses arise from the interaction of different parts of the opening mechanism, for example, the interaction of the lid with the container, or the interaction of an internal thread with an external thread.

[0008] Many of the final products are sent for recycling, where the fibers are separated and used in new products. This places special demands on the recycling operation, usually a product where only a minimal amount of fibers are bonded together so that they cannot be separated in a repulping operation. Since repulping operations benefit from thinner materials and objects, there is an advantage that when weak layers are introduced, the object will peel away and the resulting strong layers will be better exposed to the repulping operation and be able to be separated more efficiently.

[0009] Thus, there remains a need to provide products that are easily recyclable and / or compostable. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 3736099 [Patent Document 2] International Publication No. 2020 / 165780 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention solves / mitigates one or more of these problems by providing, according to a first aspect, a multi-layer substrate comprising at least one layer providing tensile strength and one layer including fibres with sufficiently low internal strength to be moulded in a press moulding operation, at least in part, to mould new bonds in new relative positions.

[0012] According to a second aspect of the present invention there is also provided a method for processing a multi-layer substrate according to any one of the preceding claims to provide a multi-layer product, the method comprising the following steps: a) providing the multilayer substrate; b) exposing the substrate to an elevated pressure; c) exposing the substrate to an elevated temperature to provide a multi-layer product; Includes.

[0013] Also according to a third aspect of the present invention there is provided a multi-layer product obtainable by a method according to the second aspect.

[0014] Also according to a fourth aspect of the invention there is provided the use of a multi-layer product by a method according to the third aspect, the product being part or parts of a moulded product such as a screw cap, a container, a bread clip or a package, the container being a disposable cup or a dairy carton or an autoclave package or a tray, or a plate for eating or storing food, or a paper or paperboard such as a folding cardboard.

[0015] There is also provided, according to a fifth aspect of the present invention, a method for recycling a multi-layer product according to the third aspect for providing recycled pulp, the method comprising the steps of: i) preferably after use of said multi-layer product, providing said multi-layer product; ii) submerging the product in a liquid, preferably water, most preferably warm water; iii) optionally adding one or more decoupling agents to the liquid; iv) subjecting the product to a shear force in the liquid to provide recycled pulp; Includes. [Means for solving the problem]

[0016] The terms "fibre" or "fiber" may be used interchangeably herein and will have the same meaning.

[0017] According to a preferred embodiment of the first aspect, the layer providing tensile strength provides a tensile strength that is at least about 10%, preferably at least about 20%, and most preferably at least about 50% higher than the tensile strength of the other layers.

[0018] According to a preferred embodiment of the first aspect, the substrate is at least a three-layer material. The substrate may further comprise more than three layers, for example 4, 5, 6, 7, 8, 9 or 10 layers.

[0019] According to a preferred embodiment of the first aspect, the high tensile strength is provided by at least one of the outer layers, preferably having a minimum tensile strength of about 75 N / m (CD) (CD=cross machine direction).

[0020] According to a preferred embodiment of the first aspect, the high tensile strength is provided by the two outer layers, preferably with a sum of the minimum tensile strength of about 150 N / m (MD), thus providing about 75 N / m, while the middle layer provides an essentially smaller portion (MD=machine direction).

[0021] According to a preferred embodiment of the first aspect, the layer(s) having high tensile strength is thinner than the central layer(s).

[0022] According to a preferred embodiment of the first aspect, the material with low initial tensile strength provides one or more layer(s) with good repulping.

[0023] According to a preferred embodiment of the first aspect, at least one of the outer layers has high hydrophobicity and / or oil repellency, preferably by using water and / or oil repellents such as AKD (alkyl ketene dimer), ASA (alkenyl succinic anhydride) or wax, or a combination thereof. This can be achieved for at least one or both of the outer layers as follows:

[0024] In this method, large cellulosic materials (approximately 7 to 8 cm 3 The cellulosic material (which may have a specific volume of about 1.11 to about 1.25 kg / dm2) is pressed after passing through a decurler unit, whereby a water and / or oil repellent is applied (e.g., using a spray) prior to pressing. The cellulosic material may be wet-laid or air-laid. A combination of pressure (about 10 to about 100 MPa, preferably about 20 to about 30 MPa) and heat (about 120 to about 250°C, preferably about 120 to about 180°C) is applied to the material for 0.5 to 2 s, which results in a high density cellulosic material (about 1.11 to about 1.25 kg / dm2) with relatively limited porosity and a relatively capillary-free structure. 3 This process affects the material in several ways: a) The high temperature at which the material is pressed allows the fiber mat to be heated above the melting point of the agent used for water / grease repellency, which allows the agent to be more evenly redistributed / spread onto / around the fibers during pressing to achieve more homogenous fiber coverage and thus high hydrophobicity and / or oil repellency. b) Extremely high densification in the material during pressing results in a smooth closed surface object with a low specific volume when compared to other cellulosic materials such as paperboard or wet-formed cellulose. Densification of the fiber network allows the creation of a network of hydrophobic and / or oleophobic agents (i.e., water- and / or oil-resistant agents) around the fibers, which are then trapped within the structure due to lack of space available for the agent to flow. Furthermore, the smooth closed surface further reduces the possibility of flow and trapping the agent within the material, which in turn reduces the possibility of hydrolysis, thus improving performance. Finally, densification of the material increases the volume fraction of hydrophobic and / or oleophobic agents (i.e., water- and / or oil-resistant agents) for a given amount of material, resulting in further densification of the network and improved performance.

[0025] The decurler unit that can be used in connection with the above-mentioned method can be, for example, a roll decal component provided by Maxson Automatic Machinery Company, or a decal unit provided by Ricoh. The decal unit can include one sponge roller, two metal rollers, and two paths for paper or other cellulosic materials. The strength and curl direction of the decal can be adjusted. It can be a "sandwich" configuration, where there is an upper pressure roller, a decal roller, and a lower roller.

[0026] According to a preferred embodiment of the first aspect, at least one of the outer layers has high relative wet strength.

[0027] According to a preferred embodiment of the first aspect, at least one of the outer layers has a high density.

[0028] According to a preferred embodiment of the first aspect, the density is about 0.5 kg / dm 3 and preferably about 0.1 to about 0.4 kg / dm 3 It is.

[0029] According to a preferred embodiment of the first aspect, the gram weight is about 100 to about 2000 g / m 2 , preferably about 300 to about 1500 g / m 2 When tissue paper is used as the starting material for one layer, preferably the outer layer, it is about 15 to about 18 g / m 2 , preferably about 16.5 g / m 2 The weight may have a number of grams.

[0030] 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%.

[0031] 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, and preferably at least one component of the additive(s) comprises fibers of a man-made polymer.

[0032] The substrate as described above for the embodiment of the first aspect may originate from CTMP (chemithermo mechanical pulp), TMP (mechanical pulp), kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton pulp, or a combination thereof. Moreover, the substrate may originate from bleached or unbleached pulp, or a combination thereof. Moreover, the substrate may originate from hard or soft wood, bagasse paper, algae or straw, or a combination thereof.

[0033] According to a preferred embodiment of the second aspect, the high pressure and temperature of steps b) and / or c) is provided by a press pad device and a stamp device.

[0034] According to a preferred embodiment of the second aspect, the substrate originates from CTMP (chemithermo mechanical pulp), TMP (mechanical pulp), kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, boards or big packs, or combinations thereof.

[0035] According to a preferred embodiment of the second aspect, the substrate originates from bleached or unbleached pulp, or a combination thereof.

[0036] According to a preferred embodiment of the second aspect, the substrate originates from hard or soft wood, bagasse paper, algae or straw, or a combination thereof.

[0037] According to a preferred embodiment of the second aspect, step a) is preceded by a delivering step which comprises shaping the substrate into a strip followed by folding said strip.

[0038] According to a preferred embodiment of the third aspect, the product according to the third aspect is a shaped product such as a screw cap, a container, a bread clip, or a package, which container may be a disposable cup or a dairy carton or an autoclave package or a tray, or a plate for eating or storing food, or a paper or paperboard such as a folding cardboard.

[0039] According to a preferred embodiment of the third aspect, a multi-layer product is provided such that one of the outer layers forms a screw or click-on feature for a sealable packaging, such as a container, a closure, or part of a container or closure.

[0040] In accordance with the present invention, materials usable in press molding operations that are capable of partially separating and rebonding fibers can be produced that have high tensile, shear and surface strength and can be delivered to the molding operation in an efficient manner.

[0041] Furthermore, the outer layer and surface properties of the molded product can be sufficiently strong and resistant to minimize the amount of reinforcing agent while still maintaining high repulpability and therefore high recyclability.

[0042] In one application of the invention, the multi-layer material is folded during or before pressing and forming operations, which creates a strong internal structure of the material where the outer layers interact. In this way, the structure can be locally reinforced while minimizing the use of strength additives and retaining recyclability.

[0043] The tensile strength and handling properties of the novel material of the present invention enable new delivery systems in which the material can be delivered in folded strips onto a pallet.

[0044] This brings two distinct advantages to the production of items, especially high volume packaging items. The delivery method is made possible by the use of a strong yet soft material resulting from the multi-layer construction, in this case allowing for a highly volumetrically efficient system due to the strength and possibility to fold without creating creases that would affect the final product. To create a block of continuous material by folding, the volumetric efficiency of sheets on a pallet is combined with the production advantages that come with a continuous feed material from a roll.

[0045] The preferred features of each aspect of the present invention are as for each of the other aspects, mutatis mutandis. The prior art document(s) referred to in this specification are incorporated to the full extent permitted by law. The present invention is further described in the following examples, taken in conjunction with the accompanying figures, which are not intended to limit the scope of the present invention in any way.

[0046] The embodiments of the present invention have been described in more detail using examples of embodiments in conjunction with the accompanying drawings, the sole purpose of which is to illustrate the invention and is in no way intended to limit its scope. [Brief description of the drawings]

[0047] [Figure 1] 1 shows a schematic diagram of multi-layer material production according to the present invention, where one or both of the outer molded layers are typically strong and carry the other layer loosely held together. [Diagram 2]A large roll of material held loosely together internally is unwound and cut into several smaller rolls which are then employed, thereby illustrating the general cutting action, subjecting the web to high tension and sharing the forces from the cutting action. [Diagram 3] Shown is a schematic forming operation in which fibrous material, partially loosely held together, is unwound, cut, pulled, draped, pressed and possibly post-cut into a multi-layered structure with extra strong inner and / or outer surfaces. [Figure 4] A schematic multi-layer molded structure is shown in which one or both of the outer layers are highly resistant to the repulping operation while the center layer is more easily separated, thereby enhancing the structure's exfoliation and repulping and therefore recyclability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Working Example 1. Illustrative Description A. Forming the first outer or inner layer B. Forming the second center layer C. Forming a third outer or inner layer D. Additional manufacturing processes in which the material is exposed to mechanical or chemical stresses. Mechanical stresses are usually imposed by compression (calender) and tensile stresses in machine or drying operations. Chemical stresses are usually imposed by moisture or water, for example from operations adding water-soluble or dispersible additives. E. Winding operations where the material is exposed to tension to produce a stable enough roll. If the tension in the winding operation is not high enough, the tension inside the roll is not enough to prevent what is called stretching during handling. F. In a winding operation, web tension is necessary to pull the material from the large original roll and must be high enough to create sufficient web tension in the resulting smaller roll to allow safe handling. Tension is usually achieved by driving the smaller roll and controlling or braking the rotation of the larger roll. G. Unwinding of converting operations. Web tension, which creates tension in the material, must result in a flat and controlled web. This is usually achieved by the material being pulled by a feeding unit and the roll being restrained by a braking mechanism. For unwinding, the layers of the roll, with the inside of the material resting against the outside of the material, must separate, creating not only tension but also out-of-plane or shear forces, which means that if the surface strength of the material is not high enough, there is a risk that the material will break, dust will be generated, or parts of one surface will stick onto the other surface. H. In some operations, the material is cut into blanks prior to the feeding operation which creates tension and shear forces on the material. I. The material as a web or sheet (or blank) is fed to the press operation (J) by a pushing action by a feeding device, usually without tension, and later the material is stamped or draped into a mold (see "Press Pad Device" in Figures 1 and 2). The pushing action creates compressive and buckling forces on the material, and as fed, the material is required to be strong and stiff enough not to compress, fold or buckle. J. Press Device (see also Figures 1 and 2 below). The material is usually pressed flat into the press area and then pressed or draped onto the press pad device using a stamp or specialized tool. The material needs to be strong enough not to break from tension or shear forces generated by the brake press device and the pad walls, while at the same time a significant amount of the fibers need to be loose enough to rearrange during the pressing action. During the pressing action, the material is molded and new bonds are formed. The nature of the material and the additives added determine the properties of the new laminate structure. Usually the material includes strength, wet strength, and hydrophobicity, and can be strong and / or resistant to water, while materials without these additives will produce properties that allow for good repulping properties. When the material is folded with a pressing or draping action, the inner or outer material will come into folds that are in direct contact with themselves, usually creating a strong reinforcing structure. K. In forming and pressing operations, the outer and / or inner layers usually result in a multi-layer structure where extra strength is imparted from additives that are added initially to create one or a few strong layers in the manufacturing and converting operations. If the formed item is cut after forming, the strength of the outer(s) aids the cutting operation by providing good shear and bending resistance.

[0049] The molded product will benefit from the extra strength.

[0050] As a non-limiting example, the minimum tensile strength may be 150 N / m (MD) total, with essentially no strength in the middle layers, and therefore each outer layer would have a tensile strength of about 75 N / m (CD). L. After use, the fibers of the item need to be recycled and made available for new use as packaging or other products. This is usually done by collecting, transporting and repulping the item together with other fibers and paper products. Repulping, which constitutes the fifth aspect of the invention, usually involves submerging the item in hot water and subjecting it to shear forces that separate the fiber bonds, with or without decoupling agents. Typically, strong bonds, additive-assisted bonds and thick structures are more difficult to repulp. M. Multilayers in which one or more layers are susceptible to delamination are delaminated or partially delaminated, and layers that are susceptible to repulping are separated into single fibers. Layers that are difficult to separate end up in thinner layers or flakes, the geometric changes of which make them more easily susceptible to separation into single fibers than if they were maintained in a thicker structure. If all or part of the stronger layers will not be totally separated, they are sorted out, allowing the main part of the structure to be recycled into new paper or textile products.

[0051] 2. Measurement When an airlaid test material (carrier sheet), which is a multi-layer material according to the present invention, is processed through a test and subsequently measured, for example, for tensile strength performed on the entire material (including tissue), data (test results) can be collected that can be expressed as follows:

[0052] [Table 1]

[0053] Extensibility and breathability of the tissue carrier are two important parameters for conversion in an airlaid machine.

[0054] Additional measurements for an exemplary thermally bonded airlaid tissue carrier are given below:

[0055] [Table 2]

[0056] Although various embodiments of the present invention have been described above, those skilled in the art will further realize slight modifications that would fall within the scope of the present invention. The scope and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only according to the following claims and their equivalents. For example, any of the layer configurations or methods described above may be combined with other known methods. Other aspects, advantages, and modifications within the scope of the present invention will be apparent to those skilled in the art to which the present invention pertains.

Claims

1. A multi-layer substrate comprising at least one layer providing tensile strength and one layer including fibers with sufficiently low internal strength to be molded in a press molding operation, at least partially forming new bonds in new relative positions.

2. 10. The multi-layer substrate of claim 1, wherein the layer providing tensile strength provides a tensile strength that is at least about 10%, preferably at least about 20%, and most preferably at least about 50% higher than the tensile strength of the other layers.

3. The multi-layer substrate of claim 1 , wherein the substrate is at least three layers of material.

4. 4. The multi-layer board of claim 3, wherein said high tensile strength is provided by at least one of said outer layers, preferably having a minimum tensile strength of about 75 N / m (CD).

5. 4. The multi-layer board of claim 3, wherein the high tensile strength is provided by the two outer layers, preferably with a sum of minimum tensile strength of about 150 N / m (MD).

6. The multi-layer board of claim 3 , wherein the high tensile strength layer(s) is thinner than the central layer(s).

7. A multi-layer board according to any one of claims 1 to 3, wherein the material with low initial tensile strength provides one or more layers with good repulpability.

8. 4. The multilayer substrate of claim 3, wherein at least one of said outer layers has high hydrophobic and / or oil repellency, preferably by using water and / or oil repellent agents such as alkyl ketene dimers, alkenyl succinic anhydrides or waxes, or combinations thereof.

9. The multi-layer board of claim 3 , wherein at least one of the outer layers has a high relative wet strength.

10. The multi-layer board of claim 3 , wherein at least one of the outer layers has a high density.

11. The density is about 0.5 kg / dm ３ and preferably from about 0.1 to about 0.4 kg / dm ３ The multilayer substrate according to any one of claims 1 to 3,

12. The gram weight is about 100 to about 2000 g / m ２ , preferably about 300 to about 1500 g / m ２ The multilayer substrate according to any one of claims 1 to 3,

13. The multilayer substrate according to any one of claims 1 to 3, wherein the moisture content is from about 4 to about 25%, preferably from about 7 to about 15%.

14. 4. The multi-layer board of claim 3, wherein at least one of the outer layers includes one or more additives for extra strength and wet strength, and preferably at least one component of the additive(s) includes fibers of a man-made polymer.

15. A method for processing a multi-layer substrate according to any one of claims 1 to 14 to provide a multi-layer product, comprising the following steps: a) providing the multi-layer substrate; b) exposing the substrate to an elevated pressure; c) providing a multi-layer product by exposing said substrate to an elevated temperature; A method comprising:

16. 16. The method of claim 15, wherein the high pressure and temperature of steps b) and / or c) is provided by a press pad device and a stamp device.

17. 16. The method of claim 15, wherein the substrate is derived from chemithermo-mechanical pulp, mechanical pulp, kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, a board or big pack, or a combination thereof.

18. The method of claim 15 , wherein the substrate is derived from bleached or unbleached pulp, or a combination thereof.

19. 16. The method of claim 15, wherein the substrate is derived from hard or soft wood, bagasse paper, algae or straw, or a combination thereof.

20. 16. The method of claim 15, wherein step a) is preceded by a delivering step that includes forming the substrate into a strip followed by folding the strip.

21. A multi-layer product obtainable by the method according to any one of claims 15 to 20.

22. 22. The multi-layer product of claim 21, wherein the product is a molded product such as a screw cap, a container, a bread clip, or a package, and the container can be a disposable cup or a dairy carton or an autoclave package or a tray, or a plate for eating or storing food, or a paper or paperboard such as a folding cardboard.

23. 22. The multi-layer product of claim 21, wherein the product is provided such that one of the outer layers forms a screw or click-on feature for a sealable package, such as a container, closure, or part of a container or closure.

24. 22. The use of the multi-layer product of claim 21, wherein the product is part or parts of a molded product such as a screw cap, a container, a bread clip, or a package, and the container can be a disposable cup or a dairy carton or an autoclave package or a tray, or a plate for eating or storing food, or a paper or paperboard such as a folding cardboard.

25. A method for recycling a multi-layer product according to any one of claims 21 to 23 to provide recycled pulp, comprising the following steps: i) providing said multi-layer product, preferably after use of said multi-layer product; ii) submerging the product in a liquid, preferably water, most preferably warm water; iii) optionally adding one or more decoupling agents to said liquid; iv) subjecting said product to shear forces in said liquid to provide recycled pulp; A method comprising:

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