Method for producing a multi-layered cloth product

Abstract

The invention relates to a method for producing a multi-layered cloth product comprising at least a cleaning layer and a core layer, each containing cellulose and / or consisting entirely of natural fibres and / or regenerated fibres, wherein the cleaning layer and the core layer are bonded together by means of hydroentanglement.

Description

[0001] Process for producing a multi-layer cloth product

[0002] The present invention relates to a method for producing multi-layer wipe products, in particular multi-layer disposable wipe products, such as disposable floor wipes.

[0003] Depending on their composition, wipe products have a wide range of uses, particularly in the cosmetic and hygiene sectors, as well as for numerous cleaning applications. Depending on the intended application, which often requires wet or moist application, the wipe products can be pre-impregnated with an impregnating agent and packaged individually or in units with a predetermined number of wipe products. They can also be packaged unsaturated and, if desired or necessary, moistened or impregnated only after removal from the packaging.

[0004] Depending on the intended application, the wipe products comprise multiple layers of nonwoven fabric, which can be of the same or different compositions. In the case of disposable wipes for cleaning surfaces, it is well known that these should comprise multiple layers of nonwoven fabric, which usually have different compositions. This ensures sufficient stability of the wipe and, with layers of nonwoven fabrics of different compositions, can ensure, for example, that a first layer provides good liquid absorption, while a second layer provides good liquid release.

[0005] WO 02 / 36339 A2, for example, describes such a multi-layer pre-soaked wipe, whose at least two layers contain a mixture of hydrophilic and hydrophobic fibers. The wipe comprises at least one cleaning layer and a layer that serves as a liquid reservoir.

[0006] A similar approach for a multi-layer disposable floor wipe is pursued in EP 1 212 478 A1. Antimicrobial properties are imparted to the floor wipes by adding preferably silver particles.

[0007] US 4298649 A describes a multi-layer floor wipe made of several layers of polypropylene with different appearance, wherein the floor wipe contains surfactants.

[0008] The disadvantage of this solution is that the floor wipe is not environmentally friendly as a disposable item due to its high plastic content.

[0009] A more environmentally friendly alternative is disclosed in WO 2018 / 017597 A1, which describes a disposable floor wipe with at least one layer. The composition of the individual layers is said to be fully compostable and degradable. A high PLA content ensures that the individual layers can be welded together.

[0010] DE 10 2021 122 041 B1 describes a multi-layer disposable floor wipe with an abrasive strip, comprising at least one cleaning layer and a core layer, both of which contain cellulose and are made entirely of natural fibers and / or regenerated fibers. A scratch strip with increased abrasive properties compared to the remaining cleaning layer is arranged on or in the cleaning layer, and the scratch strip contains hemp and is also made entirely of natural fibers and / or regenerated fibers. The cleaning layer and the core layer, as well as optional additional layers, are preferably bonded together by micro-entangling using ultrasonic motion. The object of the invention

[0011] It is the object of the present invention to provide an alternative process for producing multi-layer environmentally friendly cloth products, which preferably overcomes the aforementioned disadvantages known from the prior art and is characterized in particular by a strong and chemical-free bonding of the individual layers to one another.

[0012] General description of the invention

[0013] The invention solves this problem with the features of the claims and in particular by providing a method for producing a multi-layer wipe product comprising at least one cleaning layer and a core layer, each containing cellulose and / or consisting entirely of natural fibers and / or regenerated fibers, wherein the cleaning layer and the core layer are bonded together by means of hydroentanglement.

[0014] Optionally, in the process according to the invention, one or more additional layers, which also consist entirely of natural fibers and / or regenerated fibers, are also bonded to the cleaning layer and / or the core layer by means of hydroentanglement. A further layer can, in particular, be a cover layer consisting entirely of natural fibers and / or regenerated fibers, which is bonded to the core layer by hydroentanglement on the side of the core layer facing away from the cleaning layer.

[0015] In the context of the present invention, a "cleaning layer" refers to a layer with good liquid release. This is the layer that directly contacts the surface to be cleaned during use. However, more abstractly, the cleaning layer can also be referred to as a "first layer," which is why "cleaning layer" and "first layer" are used synonymously and interchangeably in the context of the present disclosure.

[0016] In the context of the present invention, a "core layer" refers to a layer with good liquid absorption, which serves as a storage reservoir for impregnating agent and passes it on to the cleaning layer. In more abstract terms, however, the core layer can also be referred to as a "second layer," which is why "core layer" and "second layer" are used synonymously and interchangeably in the context of the present disclosure. A "cover layer" refers to a layer in the context of the present invention that can function as a barrier layer. This additional layer can be arranged in particular on the side of the core layer facing away from the cleaning layer, where it ensures that liquid is not released upwards but exclusively downwards. The cover layer can also be referred to as the "third layer," which is why "cover layer" and "third layer" are used synonymously and interchangeably in the context of the present disclosure.

[0017] According to the invention, the cleaning layer, the core layer, the optional cover layer, and other optional layers contain natural fibers and / or regenerated fibers. "Natural fibers" are understood to mean all fibers of natural origin that can be used directly without further chemical conversion reactions. "Regenerated fibers," on the other hand, are fibers that are produced from naturally occurring, renewable raw materials through chemical processes. However, like natural fibers, regenerated fibers are also made from 100% natural materials.

[0018] Hydroentanglement has so far been known in the art exclusively for bonding individual or loose fibers, meaning that it is known that nonwovens can be produced by hydroentanglement. However, within the scope of the present invention, it has now been surprisingly discovered that already bonded nonwovens can also be bonded together using hydroentanglement.

[0019] "Nonwovens" refers to fiber-bonded materials in which the fibers have already formed a strong bond. Since hydroentanglement typically involves interlocking a loose fiber bed with the water jets, thereby bonding it together, one would not expect hydroentanglement to be used to bond already bonded nonwovens, as these no longer contain enough loose fiber ends that are not already entangled with other fibers.

[0020] However, in experiments investigating the suitability of ultrasonic bonding, needling and hydroentanglement for bonding layers of bonded nonwovens, it was found that hydroentanglement is actually the most suitable method.

[0021] Ultrasonic bonding had to address the problem that ultrasonic frequencies generate heat, which leads to thermal bonding of the fibers. However, in the absence of a thermoplastic polymer, this heat does not lead to a melting process and thus no bonding. Therefore, attempts were made to achieve a better bond by moistening the core layer. This was only partially successful, however, because although the introduced water molecules did form hydrogen bonds between the cellulose-containing layers, these bonds collapsed upon contact with an impregnating solution, causing the cloth to lose its structural integrity.

[0022] Attempts were also made to bond the cleaning layer, the core layer, and a cover layer together by needle punching. Needle punching is a process in which needles are pierced through the nonwoven, transporting the fibers from the top to the bottom. This bonds the fibers together and mechanically strengthens the nonwoven. In this case, however, it turned out that the core layer was severely damaged by the needling, forming nubs on the "out side." Nevertheless, different compositions of the individual nonwoven layers were chosen to be bonded by needle punching. In each case, however, either an adequate bond could not be achieved or the resulting wipe exhibited extremely poor lubrication, making it completely unsuitable for cleaning surfaces, and in particular for floor wipes.

[0023] With hydroentanglement, however, excellent bonds with high resilience and stability, even in contact with impregnating agents, could be created between the already highly consolidated nonwovens from which the individual layers were made.

[0024] The method according to the invention for producing a multi-layer wipe product is therefore characterized in that the cleaning layer and the core layer and optionally one or more further layers, in particular the cover layer, are produced by processing the fibers of which each of these layers consists, independently of one another, into a nonwoven fabric, i.e. consolidating them, and thus the cleaning layer, the core layer and optionally one or more further layers are each obtained as a separate nonwoven fabric, and wherein the (consolidated) nonwovens obtained in this way, which are the cleaning layer, the core layer and optionally one or more further layers, in particular the cover layer, are then bonded to one another by means of hydroentanglement.

[0025] According to one embodiment, the fibers containing the cleaning layer, the core layer, and / or the additional layer are bonded to form a nonwoven fabric using manufacturing technologies that belong to "web formation" technology or "web bonding" technology. Preferred processes belonging to "web formation" technology are carding, airlaid processes, wetlaid processes, meltblown processes, and spunlaid processes. Preferred processes belonging to "web bonding" technology, on the other hand, are calendering, hydroentanglement (hydroentanglement, spunlace), needle punch, and air-through bonding.

[0026] According to a preferred embodiment of the method according to the invention, the cleaning layer is produced by bonding / bonding hemp fibers and viscose fibers to form a nonwoven fabric, wherein the proportion of hemp fibers is preferably equal to or greater than the proportion of viscose fibers. Advantageously, the proportion of hemp fibers is approximately 50-70 wt.%, and the proportion of viscose fibers is approximately 30-50 wt.%. A preferred basis weight of the cleaning layer is 40-60 g / m². 2 and particularly preferably 50 g / m 2 .

[0027] According to a further preferred embodiment of the method according to the invention, the core layer is produced by bonding / consolidating cellulose fibers, lyocell fibers, and / or pulp, optionally with a bio-based binder and / or other plant fibers, to form a nonwoven fabric. For example, it is possible to bond exclusively cellulose fibers as the core layer in the presence of a bio-based binder using an airlaid process to form a nonwoven fabric. This nonwoven fabric has a basis weight of approximately 120-140 g / m². 2 Alternatively, it is also possible, for example, to combine pulp and lyocell fibers into a nonwoven fabric using a wet-laid process, with the pulp content being 65-85% by weight and the lyocell fiber content correspondingly 15-35% by weight. Core layers made of pulp / lyocell preferably have a basis weight of approximately 50-70 g / m². 2Alternatively, it is also possible, for example, to use other plant fibers to produce the core layer. This particularly applies to hemp fibers, which, however, also count as cellulose fibers mentioned above.

[0028] Optionally, in the process according to the invention, in addition to the cleaning layer and the core layer, another layer consisting exclusively of viscose fibers is produced by bonding the viscose fibers to form a nonwoven fabric. This layer preferably functions as a cover layer.

[0029] According to a preferred embodiment, nonwoven layers with the following compositions are produced in the process according to the invention (data in % by weight): Cover layer: 100% viscose

[0030] Cleaning layer: 70% hemp / 30% viscose

[0031] Core layer: 100% airlaid cellulose, bio-based binder

[0032] According to a further preferred embodiment, nonwoven layers having the following compositions are produced in the process according to the invention (data in wt.%):

[0033] Top layer: 100% viscose

[0034] Cleaning layer: 70% hemp / 30% viscose

[0035] Core layer: 80% pulp, 20% lyocell

[0036] According to a further preferred embodiment, nonwoven layers having the following compositions are produced in the process according to the invention (data in wt.%):

[0037] Top layer: 100% viscose

[0038] Cleaning layer: 100% CAC (Carded / Airlaid / Carded) cellulose

[0039] Core layer: 100% airlaid cellulose, bio-based binder

[0040] According to a further preferred embodiment, nonwoven layers having the following compositions are produced in the process according to the invention (data in wt.%):

[0041] Top layer: 100% viscose

[0042] Cleaning layer: 50% hemp, 50% viscose

[0043] Core layer: 100% airlaid cellulose, bio-based binder

[0044] According to a further preferred embodiment, nonwoven layers having the following compositions are produced in the process according to the invention (data in wt.%):

[0045] Top layer: 100% viscose

[0046] Cleaning layer: 100% viscose

[0047] Core layer: 100% airlaid cellulose, bio-based binder

[0048] It is noteworthy in this context that even versions with 100%

[0049] Cellulose or viscose in the cleaning layer can provide excellent lubricity for the wipe product, provided it has a 3D embossing. Without embossing, sufficient lubricity has always required the inclusion of hemp in the cleaning layer. However, it has been found that a cleaning layer made of pure cellulose or viscose exhibits at least equivalent lubricity if the wipe product has an embossing.

[0050] Preferably, the water jet consolidation of the cleaning layer with the core layer and optionally one or more further layers takes place in a device which has at least two drums in which the layers to be joined are treated with water jets, wherein the water jets in the first drum impinge on the layers to be joined with a lower pressure than in the second drum.

[0051] Preferably, the water jets in the first drum emerge from a plurality of nozzle strips, each nozzle strip in the first drum comprising a plurality of nozzles, the water jets emerging from each nozzle belonging to the same nozzle strip at the same pressure, and the pressures of the water jets emerging from nozzles belonging to different nozzle strips can be the same or different and are each between 10 and 80 bar. Preferably, there are three nozzle strips in the first drum, the pressure at which the water jets emerge from the nozzles of the first nozzle strip preferably being 10 to 30 bar, the pressure at which the water jets emerge from the nozzles of the second nozzle strip preferably being 30 to 60 bar, and the pressure at which the water jets emerge from the nozzles of the third nozzle strip preferably being 60 to 80 bar.

[0052] It is further preferred that the water jets in the second drum emerge from a plurality of nozzle strips, each nozzle strip in the second drum comprising a plurality of nozzles, the water jets emerging from each nozzle belonging to the same nozzle strip at the same pressure and the pressures of the water jets emerging from nozzles belonging to different nozzle strips being the same or different and each being between 30 and 100 bar, preferably between 60 and 100 bar, more preferably between 90 and 100 bar.

[0053] Optionally, the second drum has a nub structure, in particular a 2D nub structure, in order to achieve an embossing of the cloth product, which results in improved sliding properties.

[0054] As a result of the hydroentanglement of the cleaning layer, the core layer, and optionally one or more additional layers, these are bonded together to form the multi-layer wipe product. This is then optionally dried at temperatures above 150°C, in particular at temperatures above 170°C, and most preferably at temperatures between 175 and 200°C. The drying step preferably takes place in a multi-drum dryer in which the multi-layer wipe product is not only dried but also pressed. Alternatively or in addition to the aforementioned drying at temperatures above 150°C, the drying step can also involve the application of ultrasound to the wipe product, which is then dried by the resulting kinetic energy.

[0055] The features of the invention disclosed in the above description, in the examples and in the claims may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

Claims 1. A process for producing a multi-layer wipe product comprising at least one cleaning layer and one core layer, each containing cellulose and / or consisting entirely of natural fibers and / or regenerated fibers, wherein the cleaning layer and the core layer are bonded together by means of hydroentanglement.

2. A method for producing a multi-layer wipe product according to claim 1, characterized in that one or more optional further layers, which also consist entirely of natural fibers and / or regenerated fibers, are also bonded to the cleaning layer and / or the core layer by means of hydroentanglement.

3. A method for producing a multi-layer wipe product according to claim 1 or 2, characterized in that the cleaning layer and the core layer and optionally one or more further layers are produced by processing the fibers of which each layer consists into a nonwoven fabric and thus obtaining the cleaning layer, the core layer and optionally one or more further layers as a nonwoven fabric, and wherein the nonwovens obtained in this way, which are the cleaning layer, the core layer and optionally one or more further layers, are then bonded to one another by means of hydroentanglement.

4. A method for producing a multi-layered wipe product according to any one of the preceding claims, characterized in that the cleaning layer is produced by combining hemp fibers and viscose fibers to form a nonwoven fabric, wherein the proportion of hemp fibers is greater than the proportion of viscose fibers.

5. A method for producing a multi-layered cloth product according to any one of the preceding claims, characterized in that the core layer is produced by combining cellulose fibers, lyocell fibers and / or pulp, optionally with a bio-based binder and / or other plant fibers, to form a nonwoven fabric.

6. A method for producing a multi-layer wipe product according to any one of the preceding claims, characterized in that in addition to the cleaning layer and the core layer, a further layer consisting exclusively of viscose fibers is produced by combining the viscose fibers to form a nonwoven fabric.

7. A method for producing a multi-layer wipe product according to any one of the preceding claims, characterized in that the fibers containing the cleaning layer, the core layer and / or the further layer are joined to form a nonwoven fabric by methods which are independently selected from the group comprising airlaid processes, wetlaid processes, hydroentanglement, carding, calendering, meltblown processes, spunlaid processes, air through bonding, needling, spunbond processes and DRC processes.

8. A method for producing a multi-layer wipe product according to any one of the preceding claims, characterized in that the hydroentanglement of the cleaning layer with the core layer and optionally one or more further layers takes place in a device which has at least two drums in which the layers to be joined are treated with water jets, the water jets impinging on the layers to be joined with a lower pressure in the first drum than in the second drum.

9. A method for producing a multi-layered wipe product according to claim 8, characterized in that the water jets in the first drum emerge from a plurality of nozzle strips, each nozzle strip in the first drum having a plurality of nozzles, the water jets emerging from each nozzle belonging to the same nozzle strip at the same pressure and the pressures of the water jets emerging from nozzles belonging to different nozzle strips being the same or different and each being between 10 and 80 bar.

10. A method for producing a multi-layered cloth product according to claim 8 or claim 9, characterized in that the water jets in the second drum emerge from a plurality of nozzle strips, each nozzle strip in the second drum has a plurality of nozzles, wherein the water jets emerge from each nozzle belonging to the same nozzle strip at the same pressure and wherein the pressures of the water jets emerging from nozzles belonging to different nozzle strips can be the same or different and are each between 30 and 100 bar. Method for producing a multi-layer cloth product according to one of claims 8 to 10, characterized in that as a result of the hydroentanglement, the cleaning layer, the core layer and optionally one or more further layers are bonded to one another and the multi-layer A cloth product is obtained. A method for producing a multi-layer cloth product according to claim 11, characterized in that the multi-layer cloth product is subsequently dried at temperatures above 150°C and / or by ultrasound. A method for producing a multi-layer cloth product according to claim 12, characterized in that the drying step takes place in a multi-drum dryer in which the multi-layer cloth product is dried and pressed.