Stretchable packaging material

Abstract

A process for producing a stretchable packaging material is disclosed, comprising producing a cellulose layer from ground wood pulp, wherein the ground wood pulp has been milled to a fineness of at least about 70 °SR; and subjecting the cellulose layer to a wet creping process. A stretchable packaging material comprising a raw base paper is also disclosed. wherein the raw paper has an elongation at break in the machine direction of at least about 14%; and wherein the raw paper has a tensile strength in the machine direction of at least about 10 N / 15 mm.

Description

[0001] The present disclosure relates to a packaging material comprising stretchable paper and methods for producing the same. State of the art

[0002] In an industrial environment, items are typically transported on pallets. To keep these items bound together, they are typically wrapped with a plastic film, sometimes called stretch wrap. The plastic film is often a copolymer of LLDPE and an alpha-olefin, although other polymers such as (pure) PE and PVC can also be used. Each pallet requires a significant amount of plastic wrapping—some estimates indicate that 41 m, or approximately 0.5 kg, of plastic is needed per pallet load.

[0003] There is a growing desire to move away from plastic wrapping materials. A number of other materials have been considered, including paper. The appeal of paper lies in its easy recyclability and sustainable source. One problem with paper is that it typically does not stretch much and can have poor tensile strength, both of which make it unsuitable for stretch wrapping. Some earlier applications, such as US 2020 / 0407089, mentioned the use of creped paper as a possible wrapping material. US 2020 / 0407089 describes a creped paper produced using a dry creping process for wrapping pallets.However, the present inventors have discovered that while creped paper exhibits greater elongation than some papers, it can still exhibit relatively low elongation compared to plastic film, as well as poor tensile strength. Accordingly, it is not particularly suitable for use in industrial pallet wrapping machines designed for plastic stretch film materials. Its use would require a new machine or significant modification of existing wrapping machines designed for use with plastic stretch film.

[0004] There is a desire to produce an alternative to plastic film that is recyclable and has an elongation and tensile strength more similar to that of plastic films, so that it could be used in existing pallet wrapping machines without significant modification. Brief description of the invention

[0005] In a first aspect, there is provided a method of producing a stretchable packaging material, the method comprising producing a cellulosic layer from a ground mechanical pulp, wherein the ground mechanical pulp has been ground to a freeness of at least about 70°SR; and Subjecting the cellulose layer to a wet creping process.

[0006] In a second aspect, a stretchable packaging material is provided that can be produced using the process of the first aspect.

[0007] A third aspect involves providing a stretchable packaging material that includes a raw base paper; wherein the raw paper has an elongation at break in the machine direction of at least about 14%; and wherein the raw paper stock has a tensile strength in the machine direction of at least approximately 10 N / 15 mm. The raw paper stock can be, or comprise, the cellulose layer producible in the first aspect.

[0008] In a fourth aspect, there is provided a method of packaging an article, comprising: spirally wrapping the article with a stretchable packaging material according to the second or third aspect.

[0009] In a fifth aspect, there is provided an apparatus for packaging an article, comprising: a device for wrapping a load with an expandable packaging material, the device comprising a packaging material holder; and a stretchable packaging material loaded on the packaging material holder, wherein the stretchable packaging material is a material according to the second or third aspect. Brief description of the character Fig. Figure 1 schematically shows a stretchable packaging material as described in this document, which is used for binding an object. Detailed description

[0010] Optional and preferred features of the aspects are described below. Unless otherwise stated, each feature can be combined with any other feature and any aspect.

[0011] In a first aspect, there is provided a method of producing a stretchable packaging material, the method comprising producing a cellulosic layer from a ground mechanical pulp, wherein the ground mechanical pulp has been ground to a freeness of at least about 70°SR; and

[0012] Subjecting the cellulose layer to a wet creping process to produce a paper which may be referred to in this specification as raw base paper or crepe paper or stretch paper. wood pulp

[0013] The wood pulp and the raw paper produced from the wood pulp preferably comprise softwood fibers. Preferably, the solids content (i.e., the content of solids excluding water) of the milled wood pulp and the raw paper comprises at least 50 wt.% softwood, optionally at least 60 wt.% softwood, optionally at least 70 wt.% softwood, optionally at least 80 wt.% softwood, optionally at least 90 wt.% softwood, optionally at least 95 wt.% softwood. Other wood fibers may be present, which may include hardwood fibers. Hardwood fibers may be selected from aspen, birch, beech, oak, maple, eucalyptus, and gum. Optionally, the wood pulp contains 10 wt.% or less hardwood, optionally 5 wt.% or less hardwood, optionally 1 wt.% or less hardwood, optionally no hardwood.

[0014] The pulp and the raw paper produced from the pulp may contain 20% or less by weight of non-wood materials, such as mineral fillers; optionally 10% or less by weight of non-wood materials; optionally 5% or less by weight of non-wood materials; optionally 3% or less by weight of non-wood materials; optionally 2% or less by weight of non-wood materials. The pulp and the raw paper produced from the pulp may contain 20% or less by weight of mineral fillers; optionally 10% or less by weight of mineral fillers; optionally 5% or less by weight of mineral fillers; optionally 3% or less by weight of mineral fillers; optionally 2% or less by weight of mineral fillers. Mineral fillers include calcium carbonate, talc, clays such as kaolin, titanium dioxide, zinc oxide, and calcium sulfate.

[0015] The softwood may be selected from a first pulp selected from Canadian NBSK and a second pulp selected from Scandinavian NBSK (sometimes referred to as Nordic NBSK). NBSK means Northern Bleached Softwood Kraft. The pulp and raw base paper may comprise Canadian NBSK and Scandinavian NBSK. Scandinavian NBSK may comprise one or both of pine and spruce, optionally in a wt-wt ratio of about 1:10 to 10:1, optionally 5:1 to 1:5, optionally 5:1 to 1:1, optionally about 7:3. Scandinavian NBSK can include one or both Scots pine and Norway spruce, occasionally in a weight-to-weight ratio of about 1:10 to 10:1, optionally 5:1 to 1:5, optionally 5:1 to 1:1, optionally about 7:3.Canadian NBSK may include lodgepole pine, optionally with sugar pine, and may further include wood fibers selected from the following species: arborvitae, Douglas fir, hemlock, and larch.

[0016] The softwood pulp may comprise a first wood pulp, which may be a Canadian NBSK with a fiber length of at least 2.5 mm, optionally at least 2.6 mm, optionally at least 2.7 mm, optionally at least 2.8 mm, optionally at least 2.9 mm. The first wood pulp, which may be a Canadian NBSK, may comprise a Canadian NBSK with a fiber length of 2.5 mm to 4.2 mm, optionally from 2.6 mm to 4.0 mm, optionally from 2.7 mm to 3.5 mm. The fiber length may be measured according to FS5 ISO 16065-2.

[0017] The softwood pulp may include a second wood pulp, which may be a Scandinavian NBSK (non-woven softwood pulp) that has shorter fibers than the second pulp and a fiber length of 1.8 mm to 3 mm, optionally 1.8 mm to 2.5 mm, or optionally 1.9 mm to 2.5 mm. The fiber length may be measured according to FS5 ISO 16065-2.

[0018] The first pulp, which may be Canadian NBSK, and the second pulp, which may be Scandinavian NBSK, may be present in the pulp and the raw paper stock in a wt-wt ratio of 1:4 to 4:1, optionally from 4:1 to 1:1, optionally from 3:1 to 1:1, optionally from 80:20 to 60:40, optionally about 70:30. The present inventors have found that the softwood, particularly a combination of Canadian NBSK and Scandinavian NBSK, supports the production of paper with the desired elongation and tensile strength. Grind

[0019] The mechanical pulp is ground during the process of producing the cellulose layer. Mechanical pulping is a process of mechanically treating the fibers while they are suspended in a liquid, such as water. The grinding can be carried out in a refiner, which can be selected from a cone refiner and a disc refiner. A disc refiner has two opposing discs between which the mechanical pulp is passed. On the opposite surface of each disc (i.e., the surface facing the other disc), ridges or teeth protrude from its surface toward the other disc. During operation, one disc rotates relative to the other, and the mechanical pulp passes between them (and between the ridges or teeth of the discs). A cone refiner is similar to a disc refiner, except that the rotating sections are shaped like cones instead of discs.The relative rotation can be achieved by rotating one disc (or cone) while the other disc (or cone) remains stationary, or by rotating both discs (or both cones) in opposite directions. The pulp can be passed through one or more refiners to achieve a desired degree of freeness. Optionally, the pulp can be passed through a plurality of refiners arranged in series.

[0020] The purpose of milling is to (i) increase the amount of water in the wood cells, (ii) cause fibrillation, thus increasing the surface area of ​​the fibers, and (ii) delamination of the wood cell walls.

[0021] The present inventors have found that beating the pulp to a relatively high degree increases both the elongation of the paper and its tensile strength. The pulp is preferably beaten to a freeness of at least about 70°SR, optionally at least about 75°SR, optionally at least about 80°SR, optionally at least about 85°SR. The pulp is preferably beaten to a freeness of from 70°SR to 95°SR, optionally from 75°SR to 95°SR, optionally from 75°SR to 90°SR, optionally from 80°SR to 90°SR, optionally about 85°SR. "SR" indicates Schopper-Riegler, i.e., the Schopper-Riegler test for measuring the freeness of a suspension of paper fibers in water. The freeness determined by the Schopper-Riegler test can be measured according to the method described in ISO 5267 / 1-1:1999. The wood pulp can contain 2 to 5 wt% solids during milling (with the remaining wt% being water).

[0022] The cellulose layer, which can also be called paper or raw paper, can be formed from wood pulp in a paper machine. Formation of the cellulose layer

[0023] After milling, the ground wood pulp can be processed into a cellulose layer, i.e., a paper layer, in a paper machine and wet-creped. The paper machine can be a Fourdrinier paper machine. The paper machine can have the following sections: a forming section, a press section, and a drying section. In the forming section, the pulp is applied to a wire cloth to allow the water to drain from the pulp; the wire cloth can be made of a metallic or polymeric material. The milled pulp can be diluted, if desired, so that when applied to the wire cloth it contains 0.3 wt% to 1 wt% solids, optionally about 0.3 wt% to 0.7 wt% solids. In the forming section, some of the water in the pulp passes through the wire cloth, leaving a wet cellulose layer on the cloth.In the press section, the cellulose layer can be passed between one or more pairs of rollers, optionally two or more, or optionally three or more pairs of rollers. This presses more water out of the cellulose layer. In the dryer section, heat is applied to the cellulose layer to cause water to evaporate. The heat can be applied by heated rollers, sometimes referred to as a dryer drum or cylinder. Wet creping preferably takes place in the press or dryer section, provided that the creping is wet creping, i.e., the paper has a minimum amount of water, as specified in this document at the point of creping. Wet creping can take place on one of the pairs of rollers in the press section immediately before the dryer section, so that if there are three pairs of rollers in the press section, the wet creping would take place on one of the third pair of rollers.The paper machine may have a post-processing section, for example, to apply a coating substance to one or both sides of the cellulose layer. The coating substance may be a sizing substance and / or a hydrophobic substance. Wet crepes

[0024] A creping process is a process in which the cellulose layer is compressed along its running direction in a paper machine. This causes the cellulose layer to be folded or creped. This can be achieved by a doctor blade, occasionally called a creping blade. The doctor blade can be arranged parallel to the axis of a roll or perpendicular to the running direction of a conveyor on which the cellulose layer is conveyed, so that it extends across substantially the entire or at least the entire width of the paper (where the width is perpendicular to the direction of travel of the cellulose layer in the paper machine). The roll can be a roll or a conveyor in the press section or the dryer section of a paper machine.

[0025] A wet creping process can be considered a process in which the dry matter content (i.e., the non-water content) of the cellulose layer, measured immediately before creping, is 80 wt% or less, optionally 70 wt% or less, optionally 60 wt% or less, optionally 50 wt% or less, optionally 40 wt% or less. In other words, a wet creping process can be considered a process in which the moisture content (i.e., the water content or non-dry matter content) of the cellulose layer, measured immediately before creping, is 20 wt% or more, optionally 30 wt% or more, optionally 40 wt% or more, optionally 50 wt% or more, optionally 60 wt% or more.

[0026] Optionally, a wet creping process can be a process in which the dry content (i.e., the content other than water) of the cellulose layer, measured immediately before creping, is 80 wt.% to 10 wt.%, optionally 70 wt.% to 10 wt.%, optionally 60 wt.% to 10 wt.%, optionally 50 wt.% to 10 wt.%, optionally 80 wt.% to 20 wt.%, optionally 70 wt.% to 20 wt.%, optionally 60 wt.% to 20 wt.%, optionally 50 wt.% to 20 wt.%, optionally 80 wt.% to 30 wt.%, optionally 70 wt.% to 30 wt.%, optionally 60 wt.% to 30 wt.%, optionally 50 wt.% to 30 wt.%, optionally 40 wt.% to 30 wt.%, optionally about 35 wt.%.

[0027] After wet creping, the cellulose layer can be dried, for example, by conveying it to a drying section of a paper machine. The cellulose layer can be conveyed on a drying felt to the drying section (or, if creping is performed in the drying section, further conveyed in the drying section). The drying felt can be in a slalom configuration with a plurality of heated rolls (e.g., such that the cellulose layer on one roll directly contacts the heated roll and on the next roll the felt directly contacts the heated roll, or vice versa, and this then alternates from roll to roll). The drying felt can comprise a monofilament fabric or a multifilament fabric. A drying felt can be a web containing apertures and formed from a non-metallic, e.g., polymeric and / or glassy, ​​material(s). The felt can be a nonwoven or a woven fabric.The polymeric material of the felt can be selected from polyester, nylon, or acrylic. In a multifilament cloth, the filament materials can be a variety of materials, selected from nylon, fiberglass, and acrylic polymers. The cellulose layer is conveyed at an appropriate speed and tension to ensure that it does not tear or otherwise become damaged during drying. A lower tension maintains the elongation and tensile strength properties of the cellulose layer.

[0028] The drying section may be a section in which the cellulose layer is heated to cause water evaporation. The heat may be applied by heated rollers, sometimes referred to as dryer drums or rolls, which may be Yankee dryers. The heated rollers may themselves be heated by steam and, as such, may be steam dryer cylinders.

[0029] After the cellulose layer has dried, the layer can be wound into a roll, which can be referred to as a reel. The reel, with the cellulose layer or paper, can then be transferred to the post-processing device, where the cellulose layer is unwound, treated as desired, e.g., by applying a surface sizing agent, which can include a hydrophobic polymer and / or a suitable mineral, e.g., alkyl ketene dimer, a latex, and / or kaolin, to one or both sides to act as a moisture barrier / waterproofing agent, and then rewound into a roll or reel for storage. Cutting to a desired width can be performed before or during post-processing. The creped and dried cellulose layer can be referred to as raw base paper. Stretchable packaging material

[0030] In a second aspect, a stretchable packaging material is provided that can be produced using the process of the first aspect. The cellulose layer can be described as paper or raw paper and it can have a machine-directed elongation at break of at least approximately 14%; and / or the cellulose layer, which can be described as paper or raw paper, can have a machine-directed tensile strength of at least approximately 10 N / 15 mm.

[0031] In a third aspect, a stretchable packaging material is provided, comprising a cellulose layer which may be referred to as raw base paper; wherein the cellulose layer or raw base paper has an elongation at break in the machine direction of at least about 14%; and wherein the cellulose layer or the raw paper has a tensile strength in the machine direction of at least about 10 N / 15 mm.

[0032] The cellulose layer or the raw base paper can have a basis weight of 10 g / m 2 up to 150 g / m 2 , optionally 20 g / m 2 up to 150 g / m 2 , optionally 20 g / m 2 up to 120 g / m 2 , optionally 20 g / m 2 up to 100 g / m 2 , optionally 20 g / m 2 up to 80 g / m 2 , optionally 20 g / m 2 up to 70 g / m 2 , optionally 30 g / m 2 up to 60 g / m 2 , optionally 30 g / m 2 up to 60 g / m 2 , have a basis weight of 100 g / m². The basis weight can be measured according to ISO 536.

[0033] The cellulose layer or raw paper can have a thickness of 0.03 mm to 0.45 mm, optionally 0.08 mm to 0.3 mm, optionally 0.1 mm to 0.3 mm, optionally 0.1 mm to 0.25 mm, optionally 0.1 mm to 0.2 mm, optionally 0.12 mm to 0.17 mm, optionally 0.13 mm to 0.17 mm, optionally 0.14 mm to 0.15 mm.

[0034] The cellulose layer or the raw paper stock has a tensile strength in the machine direction of at least approximately 10 N / 15 mm, optionally at least 15 N / 15 mm, optionally at least 20 N / 15 mm, optionally at least 25 N / 15 mm, optionally at least 27 N / 15 mm, optionally at least 30 N / 15 mm. The tensile strength in the machine direction can be measured according to ISO 1924-2.

[0035] The cellulose layer or the raw paper stock has a tensile strength in the transverse direction of at least approximately 5 N / 15 mm, optionally at least 7.5 N / 15 mm, optionally at least 10 N / 15 mm, optionally at least 12.5 N / 15 mm, optionally at least 15 N / 15 mm. The tensile strength in the transverse direction can be measured according to ISO 1924-2.

[0036] The cellulose layer or the base paper can have a machine-directed elongation at break of at least approximately 14%, optionally at least approximately 15%, optionally at least approximately 16%, optionally at least approximately 17%, optionally at least approximately 18%. The machine-directed elongation at break can be measured according to ISO 1924-2.

[0037] The cellulose layer or the base paper can have a transverse elongation at break of at least approximately 3%, optionally at least approximately 4%, optionally at least approximately 5%, optionally at least approximately 6%, optionally at least approximately 7%. The transverse elongation at break can be measured according to ISO 1924-2.

[0038] The cellulose layer or base paper can have a Gurley smoothness of 5 s 200 ml to 50 s 200 ml, optionally from 10 s 200 ml to 30 s 200 ml, optionally from 15 s 200 ml to 25 s 200 ml. The Gurley smoothness can be measured according to procedures, e.g., ASTM D202-77, or in established standards, e.g., ASTM.

[0039] In a fourth aspect, there is provided a method of packaging an article, comprising: Wrapping the article with a stretchable packaging material according to the second or third aspect. The article may be on an industrial pallet during wrapping, and the article may be spirally wrapped. If a device is used for wrapping, the device may be a wrapping machine that wraps the article. An industrial pallet may be defined as a pallet for use in industry for transporting goods. A pallet may have both width and length dimensions of 50 cm to 150 cm and a height less than the width and length, e.g., from 5 to 20 cm.Some pallets have standardized sizes, for example an "English" pallet with a length of 120 cm, a width of 120 cm and a height of 14.4 cm, a "Euro" pallet with a length of 120 cm, a width of 80 cm and a height of 14.5 cm, a "Finpal" with a length of 120 cm, a width of 100 cm and a height of 14.4 cm.

[0040] The stretchable packaging material (i.e., the creped paper described in this document) can be supplied on a roll for use on an industrial pallet wrapping machine. The roll of stretchable packaging material (i.e., the creped paper described in this document) can have a length along its axis of 10 to 200 cm, optionally 30 to 150 cm, optionally 30 to 100 cm, optionally 30 to 70 cm, or optionally approximately 50 cm.

[0041] In a fifth aspect, there is provided an apparatus for packaging an article, comprising: a device for wrapping a load with an expandable packaging material, the device comprising a packaging material holder; and a stretchable packaging material loaded onto the packaging material holder, wherein the stretchable packaging material is a material according to the second or third aspect. The device may be a machine for wrapping articles on a pallet. The device may be computer-controlled. The device may comprise a turntable on which the pallet may sit, the turntable rotating as the stretchable packaging material is wrapped onto the article, and a dispensing device that dispenses the stretchable packaging material as the article is wrapped, e.g., from a reel of the stretchable packaging material. The dispensing device may move vertically (either upwards or downwards) during wrapping to effect spiral wrapping of the article. In an alternative embodiment, the device or a part of the device, e.g.,The dispensing device rotates the object to effect the wrapping of the stretchable packaging material around it. The device may include a stretching element that stretches the stretchable packaging material on the object. Alternatively, the wrapping of the stretchable packaging material around the object itself may cause the stretchable packaging material to stretch. The device may be handheld. The stretchable packaging material may be located on a drum attached to the device.

[0042] The use of the stretchable packaging material described in this document is further detailed below with reference to Fig. 1 described. In Fig.Figure 1 is a turntable 1 with an object 2 on it, resting on a pallet (the object's base is covered by stretchable packaging material 3, not shown). As the turntable is rotated counterclockwise, the stretchable packaging material 3 is wrapped around the object 2. The stretchable packaging material 3 is in the form of creped paper produced according to the method and has the properties described in this document. The creped paper is fed by a tambour 4, which is mounted on a roller 5. The roller is motorized and remotely controlled to allow for a feeding speed suitable for the rotational speed of the object 2 on the remotely controlled turntable 1.The creped paper is fed from the drum 4, optionally via a possibly optional stretching device 6, which is in the form of a plurality of vertical rollers exhibiting different tangential speeds, thus allowing the creped paper to be stretched to a suitable degree between them. Alternatively, if no stretching device is present, the wrapping of the creped paper around the object 1 can itself effect the stretching. The creped paper is fed from the stretching device 6 (or otherwise from the drum 4) to a dispensing device 16, which is a roller capable of moving vertically to apply the creped paper to the appropriate height on the object 1.The creped paper 3 is typically wrapped spirally around the article 1, so that the dispenser moves vertically during wrapping (upward if wrapping starts at the base of the article 1, or downward if wrapping starts at the top of the article 1). Adhesive 3 may, if desired, be applied to the creped paper by an adhesive applicator 8, which can move on a guide rod 9. The adhesive 3 may allow the creped paper to stick to itself as it wraps around the article 1. However, the creped paper will typically bond to itself without the adhesive due to friction between layers of creped paper and the stretching properties of the creped papers—the adhesive simply serves as an additional means of attaching the paper to itself.In the factory, the application of the creped paper to item 1 can be automated and controlled by a computer.

[0043] In an alternative embodiment, the crepe paper can be applied to an object manually, for example, by simply wrapping a sheet of crepe paper around the object by hand, or alternatively, by a device that can dispense the crepe paper from a roll. A handheld device can include means for receiving a tambour of crepe paper, such as a shaft / roller on which the tambour can sit, and any other means that assists in the manual application of the paper to an object, such as a handle for holding the device and / or a cutting means for cutting the paper after it has been dispensed.

[0044] A number of standard measurement methods (e.g., ASTM or ISO) are mentioned in this document. Unless otherwise stated, the most recent version of the standard measurement method, i.e., the most recent version as of the filing date of this application, shall be used.

[0045] Whenever raw base paper is mentioned in this document, “raw base paper” may also be referred to as “creped paper” or “cellulose layer” or “stretch paper”. ExamplesExample 1Production of stretch paper using a wet creping process

[0046] In a papermaking facility, a mixture of two types of NBSK softwood—70% by weight Canadian NBSK and 30% by weight Scandinavian NBSK—was used to produce a pulp (or stock) with water in a pulper. (Before use, both types of NBSK were delivered in the form of baled boards.) The pulp was then stored in chests until needed; the consistency (solids content) of the pulp at this point was 4% by weight. The pulp was then beaten to a degree of at least 85°, as measured by the Schopper-Riegler test. The beaten pulp was then diluted with water to a consistency of 0.5–1% by weight and pumped via the headbox to the wire section of a Fourdrinier paper machine. The fiber then passes the press section of the machine, passes three press nips and is creped on the creping cylinder (upper roller of the 3rd press) of the third press nip.At the point where creping was carried out with a doctor blade, the dry content of the pulp was about 35 wt% (i.e. about 65 wt% water), i.e. it is a wet creping process.

[0047] After the doctor blade, the paper is guided over a slalom felt to and through the dryer section. In the dryer section of the machine, the paper is dried using steam-heated drying cylinders (sometimes referred to as rolls), after which it is wound into a roll at the end of the machine.

[0048] The paper can then be placed on the finishing equipment, where it is unwound and treated as desired, for example, by applying a surface sizing agent, which may contain a hydrophobic polymer and / or a suitable mineral such as an alkyl ketene dimer, a latex, and / or kaolin, to one or both sides to act as a moisture barrier / hydrophobic agent. It is then rewound into a roll for storage. Cutting to a desired width can be performed before or during finishing. The stretch paper was measured with respect to its various properties, and these are listed in Table 1 below. Table 1 Characteristic units Test Value Basis weight [g / m 2 ] ISO 536 45 Strength [mm] According to ISO 534 0,145 Tensile strength, machine direction [N / 15 mm] ISO 1924-2 30 Tensile strength, transverse direction [N / 15 mm] ISO 1924-2 15 Stretching, machine direction [%] ISO 1924-2 18 Stretching, transverse direction [%] ISO 1924-2 7 Tensile strength according to Elemendorf, machine direction [mN] DIN EN ISO 1974 500 Tensile strength according to Elemendorf, transverse direction [mN] DIN EN ISO 1974 Air permeability, textile surface structures [l / m 2 s] DIN EN ISO 9237 35 Gurley smoothing [200 ml] ASTM D202-77 21

[0049] Particularly noteworthy is that the machine direction elongation was high at 18% compared to other papers. Nevertheless, the machine direction tensile strength was also relatively high at 30 N / 15 mm. Prior to the present disclosure, a combination of high elongation and high tensile strength was difficult to achieve. Additionally, the paper had a suitable surface roughness to provide a relatively high-friction surface, which is useful for use as wrapping paper. Example 2Use of paper in an industrial stretch film machine

[0050] The stretch wrap paper prepared in Example 1 was loaded as a roll into an industrial stretch wrap machine commonly used for stretch wrapping polymeric films, instead of the usual roll of polymeric film. The machine was operated under essentially the same conditions as those used for the polymeric film to wrap a cuboid-shaped object on a pallet, except that the tension may be slightly less than for a polymeric film. The paper was successfully wrapped around the object on the pallet, stretching around the object and holding it tightly (due to the frictional tension between the paper layers) in the same way as a polymeric film. This demonstrates that the stretch paper can be used in place of a polymeric film with minimal adaptation of a stretch wrap machine.Using paper as stretch wrap means avoiding the use of polymeric shrink wrap, which can be beneficial from an environmental perspective. The stretch wrap paper can be recycled after use in wrapping an item.

[0051] In addition to industrial applications, such as wrapping items on pallets, stretch wrap can be used for any other item requiring packaging. For example, it could be used as labels on containers, with optional printing before or after wrapping, or to hold one or more items together. It can be used in any environment, including a home, to wrap objects, and it doesn't require a machine to do this—it can even be done by hand. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2020 / 0407089

[0003] Cited non-patent literature

[0000] ISO 5267 / 1-1:1999

[0021]

Claims

[1] Method for producing a stretchable packaging material, the method comprising the following Producing a cellulose layer from ground wood material, wherein the ground wood material has been ground to a fineness of at least about 70 °SR; and Subjecting the cellulose layer to a wet creping process. [2] Method according to claim 1, wherein the ground wood material has been ground to a degree of fineness of at least about 75 °SR, optionally at least about 80 °SR. [3] Method according to claim 1 or claim 2, wherein the solids content of the ground wood material comprises at least 80 wt.% softwood, optionally at least 90 wt.% softwood. [4] Method according to claim 3, wherein the softwood contains Canadian NBSK and Scandinavian NBSK. [5] Method according to claim 4, wherein the Canadian NBSK and the Scandinavian NBSK are present in a weight ratio of 1:4 to 4:1, optionally 4:1 to 1:

1. [6] Method according to any of the preceding claims, wherein the dry content of the paper immediately before creping is 70 wt.% or less, optionally 50 wt.% or less, optionally 40 wt.% or less. [7] Method according to any of the preceding claims, wherein the paper is coated on at least one side with a sizing or hydrophobic substance after the wet creping process. [8] Stretchable packaging material comprising a raw base paper; wherein the raw paper has an elongation at break in the machine direction of at least about 14%; and wherein the raw paper has a tensile strength in the machine direction of at least approximately 10 N / 15 mm. [9] Stretchable packaging material comprising a raw base paper, wherein the raw base paper is or comprises a cellulose layer producible according to any one of claims 1 to 7, wherein the raw base paper is optionally defined as in claim 8. [10] Stretchable packaging material according to claim 8 or 9, wherein the raw base paper has a basis weight of 30 to 80 g / m² 2 exhibits. [11] Stretchable packaging material according to any one of claims 8 to 10, wherein the raw paper is formed from fibrous material comprising Canadian NBSK and Scandinavian NBSK, and which are optionally present in the raw paper in a wt.w. ratio of 1:4 to 4:1, optionally from 4:1 to 1:

1. [12] Methods for packaging an item, comprising: Wrapping the object with a stretchable packaging material according to one of claims 8 to 11. [13] Device for packaging an item, comprising: a device for wrapping a load with a stretchable packaging material, wherein the device comprises a packaging material holder; and a stretchable packaging material loaded onto the packaging material holder, wherein the stretchable packaging material is a material according to any one of claims 8 to 11. [14] Method according to claim 12, wherein the object is located on an industrial pallet during the wrapping process and the object is spirally wrapped with a device according to claim 13. [15] Method according to claim 14, wherein the device is a wrapping machine for wrapping an object or objects on the industrial pallet with stretch film.

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