Method for manufacturing a nonwoven sheet material having an impermeable layer on one side and an anti-slip coating on the other side

Abstract

The method includes carding (2) fibers (1) having a common general orientation to form a web, bonding (4) the fibers into a nonwoven sheet material, applying (7) a non-slip coating onto one side of the material, applying a polymer onto the second side of the nonwoven material, and maintaining the fiber orientation throughout the process.

Description

[Technical field]

[0001] The present invention relates to the field of temporary protection used to protect surfaces during operations that are subject to splashes of liquids or that degrade the surface. [Background technology]

[0002] Disposable or single-use protective devices for temporary protection of surfaces such as floors, furniture, stairs or glass windows, for example during renovation work or against children's play, have been on the market for some 20 years. In particular, impermeable and non-slip fleece or sheet materials are very popular. They consist of three layers: a central layer of nonwoven material, a top layer of an impermeable barrier or liquid-tight or waterproof membrane, and a bottom layer of a non-slip coating.

[0003] Such impermeable anti-slip sheeting materials must be tear-resistant and support people walking on them and the work equipment placed on them, such as ladders. To some extent, the material should also be durable enough to be reused several times. It is also necessary to ensure impermeability over the life of the product. The quality of the anti-slip coating is of paramount importance for the safety of the user. However, impermeability should not prevent the breathability of the material.

[0004] To date, such three-layer materials have been produced in the following way:

[0005] In a first step, the nonwoven layer is produced. A web of roughly parallel oriented fibres is prepared from staple fibres in a carding machine. The web is then placed in a crosswrapper, which successively folds and stacks the layers of the web, slowly moving the bottom of the stack vertically (Figure 1). Crosswrapping ensures, on the one hand, the durability of the material and, on the other hand, the longitudinal and transverse resistance of the nonwoven at the same time. In fact, after this operation, the fibres are arranged according to a random orientation. The web obtained is then bonded by mechanical, chemical and / or thermal operations and is usually bonded to a thickness of around 120 g / m2. 2 It will be a nonwoven material weighing more than 100 kg.

[0006] The second step is to apply an anti-slip coating to one side of the nonwoven material, typically an acrylic binder, with or without a tackifier, sprayed onto the nonwoven.

[0007] In the final step, a polymeric impermeable layer is laminated from the membrane or foil to the other side of the nonwoven material.

[0008] This production method is called the L-process because the crosslapper creates a 90° angular deviation in the placement of the production line equipment.

[0009] Whilst this method produces a very durable impermeable anti-slip sheet material, its production volumes are very limited. The cross-lapping process is limited to an output speed of about 25 m / min. Similar limitations apply to the lamination process, which is usually carried out using hot melt and infrared heaters.

[0010] In view of the high demand for such impermeable anti-slip products, Applicant has determined that it is necessary to explore new manufacturing methods that can improve production rates or speeds and, as a result, reduce manufacturing costs. Summary of the Invention

[0011] To this effect, the Applicant discloses a method for producing a nonwoven sheet material having an impermeable layer on one side and an anti-slip coating on the other side, comprising the steps of: carding fibers having a common general orientation to form a web; bonding the fibers into a nonwoven sheet material; applying an anti-slip coating to one surface of the nonwoven sheet material; applying a polymer to a second surface of the nonwoven sheet material; and Maintaining fiber orientation throughout the process The present invention proposes a method further comprising:

[0012] Therefore, the method in the present case can be called a parallel or inline process, or even a unidirectional process, which means that there is no cross wrapping applied to the fibrous web before bonding. Therefore, no angles are introduced into the series of devices involved in the process, and the devices for carding, bonding, application of anti-slip and impermeable polymers are arranged in a straight line.

[0013] The in-line production of nonwoven sheet material has been known for several years. The production process can be run at over 200 m / min, using up to three parallel carding machines with three layers superimposed before bonding, and can produce much lighter weight sheets than those typically used for impermeable anti-slip protection, i.e., but not limited to, a minimum weight of about 100 g / m 2 or about 120 g / m 2 , but not limited to, maximum weight 180g / m 2 Furthermore, the fibers of such nonwoven material sheets are essentially parallel, which results in a significant loss of lateral strength of the material.

[0014] Historically, the manufacturing process for impermeable anti-slip materials was speed limited in any case by the lamination of the impermeable barrier, so replacing the L-process to produce nonwoven materials in an in-line process was never considered, as the substitution would likely have had disadvantages, such as loss of cross-directional strength.

[0015] Only recently have techniques become available for industrially applying polymers to large surfaces at speeds of up to 200 m / min. For example, impermeable polymers can be applied by high-speed lamination, for example using electromagnetic heating, ultrasonication, hot melt adhesives or wide web spray lamination. Impermeable polymers can also be applied by spraying extruded / molten polymer onto the nonwoven material. Other techniques that allow high-speed polymer application are or may become available and should also be encompassed by the claims of the present invention.

[0016] By high speed is to be understood a line speed which is higher than the current speed of 25 m / min currently in use, for example higher than 50 m / min, preferably higher than 100 m / min.

[0017] It has been found that by replacing the L-process for producing the nonwoven material with an in-line process, and also replacing the standard lamination of the impermeable layer with the above-mentioned high speed technology, the resulting impermeable barrier provides sufficient resistance to the final product to compensate for the loss of lateral strength in the nonwoven layer.

[0018] By boldly replacing two steps of the process, i.e. two devices of the production line, the applicant has overcome the disadvantage of a lower quality of the final product. The newly proposed method herein allows the production speed of the impermeable non-slip nonwoven sheet material to be increased by up to about 10 times, while maintaining very good resistance in all directions of the final product, and the density / weight of the central nonwoven layer to about 120 g / m 2 This is why the method of the present invention involves the necessary inventive step.

[0019] Furthermore, until now the anti-slip layer was an acrylic binder applied by spray drying technology, which also limited the speed of the process. The applicants have explored replacing this process with technology that allows for faster output and have found that other materials, such as but not limited to polyurethane coatings, can be applied at speeds of up to 200m / min.

[0020] The advantage of using an in-line process is that several carding machines, usually up to three, can operate in parallel, and the parallel webs are overlapped just prior to bonding. The webs can be made of similar fibers, but it is interesting to note that different blends of fibers can be used in each web, each blend imparting specific properties to the resulting bonded nonwoven material. One blend of fibers can, for example, be flame retardant, while another blend can impart hydrophobicity.

[0021] For the Applicant's protection, a product obtained by this method is also claimed, said product being a nonwoven sheet material having an impermeable layer on one side and an anti-slip coating on the other side, characterised in that the fibres of the nonwoven sheet material have a common general orientation.

[0022] The common general direction referred to is the machine direction (MD), known to those skilled in the art.

[0023] The product is entirely related to the claimed method by the unique inventive concept of maintaining the fibers along a common general orientation.

[0024] The invention will be better understood from the following description of some examples, taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a block diagram showing an L-process according to the prior art. [Diagram 2] FIG. 1 is a block diagram showing an implementation of the method of the present invention. [Diagram 3] 1 shows a cross section of a product of the present invention. [Figure 4] 1 shows a cross section of a product of the present invention including additional layers.

[0026] With reference to FIG. 2, in a first step, raw fibres contained in a bale opener 1 are introduced into a carding machine 2, where they are carded in one direction into a web. The web is then moved along the line by a conveyor belt 3. In a second step, the fibres of the web are bonded in an oven 4 before passing through a cooling zone 5. In a next step, the bonded nonwoven material is sprayed on one of its surfaces with an extrusion polymer, i.e. a polymer melted in an extruder 6. In a final step, an anti-slip coating is sprayed on its other surface in a coating machine 7. The product obtained is now further wound up by a winding device 8. Here, an optional needling module 9 is inserted between the carding and bonding steps.

[0027] For clarity of illustration, only one bale opener 1 and one carding machine are shown, however, as will be clear to a person skilled in the art, multiple bale openers and multiple carding machines may be provided depending on the specifications of the material to be produced.

[0028] Performing this method produces an article 10, as shown in Figure 3. A nonwoven material layer 11 made from a plurality of fibers 14 is covered on one side by an impermeable layer 12 and on the other side by an anti-slip coating 13.

[0029] Carding is a mechanical process that loosens, cleans, and mixes fibers to produce a continuous web suitable for further processing. This is accomplished by passing the fibers between clothed, moving, different surfaces. This breaks up clumps and unorganized bundles of fibers and aligns the individual fibers so that they are parallel to each other. The fibers are not straight elements and are not strictly parallel, but are oriented in a common general direction overall, as shown in Figure 3. Furthermore, the fact that the fibers are not straight elements creates points of contact between the fibers, and these contact points are the bonding points during the bonding process.

[0030] Depending on the expected thickness and / or weight of the nonwoven material, several layers of carded fibers of the same or different composition can be layered before bonding, using techniques and equipment known to those skilled in the art. Using several carding machines in parallel, usually up to three, allows working at high speeds. The resulting web is then layered before bonding, or before needling, if the process is equipped with it. This also presents the advantage that the different properties of several fiber blends can be combined.

[0031] In this in-line configuration, the overall thickness of the nonwoven fabric depends on the thickness of the web leaving each carding machine and the number of carding machines operating in parallel. Typically, no more than three carding machines are used in parallel, and the resulting nonwoven fabric weight is about 200 g / m 2 , preferably 120 g / m 2 Furthermore, the general orientation imparted to the fibers in the carding process is maintained in the bonding process, so that the nonwoven fabric has high tear resistance in the machine direction, which is parallel to the general orientation of the fibers, and less tear resistance in the cross direction.

[0032] This should be distinguished from the prior art L-process (Figure 1), in which the cross-lapping step may result in ten or more layers of webs of carded fibres, and furthermore may result in deviations in the general orientation of the fibres that differ between two successive layers. Cross-lapping therefore produces much thicker carded fibres, typically 120 g / m2, than when using an in-line process. 2 The resulting nonwoven material also has high tear resistance in all directions.

[0033] An optional needling step allows fibers to intermingle in the vertical direction, which is especially recommended when multiple carding machines are used. Vertical direction here refers to the direction perpendicular to the machine direction and transverse direction disclosed in the previous paragraph, i.e., across the various layers of the web. Needling can entangle the fibers to obtain better adhesion of the web layers. Hydroentangling can be used instead of or in addition to needling. Needling and hydroentangling are techniques well known to those skilled in the art. Other reinforcing techniques can also be used, such as, for example, polymer extrusion, chemical bonding, either by knife-over-roll or any suitable coating technique, as known to those skilled in the art.

[0034] The bonding of the fibers to complete the nonwoven layer can be carried out using different techniques, such as mechanical bonding or chemical bonding. In this case, the bonding preferably includes a step of thermal bonding, alone or in combination with another technique. Preferably, the nonwoven of the present invention is a dry-laid thermal bonded nonwoven. A combination of mechanical, chemical and thermal bonding can also be selected.

[0035] The fibers used in the nonwoven material can be of any type or any blend of any suitable combination, for example a blend of 100% PET fibers (fiber thicknesses ranging from 1.7dt to 17dt), a blend of 100% PET fibers with bonded fibers bico PET / CoPET with thicknesses of 2, 4, 6 or 15dn, a blend of 100% PLA fibers, a biodegradable fiber, a blend of PET structural fibers with other bico fibers made of alternative polymers such as PET / PP, PET / PE, PP / PE, a blend of PET and viscose fibers, a blend of PET and cellulose fibers, or a blend of any of the above further including PA fibers. As already mentioned, each carding layer can be made of different blends of fibers or the same blend of fibers. Any combination can be carried out depending on the properties of the final expected nonwoven material layers.

[0036] The heat treatments usually applied to carded fibres range from 30°C to 250°C, preferably from 130°C to 140°C, depending on the nature of the fibres and the temperature required for bonding.

[0037] The weight of the nonwoven material obtained in the previous process is usually about 180 g / m 2 The weight of the sintered body may be less than 100 g, but in some cases may be even higher.

[0038] Spray extrusion of the polymer forming the impermeable layer can be carried out, for example, with PET, PE, PP, PU, ​​PTFE, TPU, PLA or PVC. The polymer is sprayed by hot melt extrusion at a temperature above its melting temperature or glass transition temperature or a combination thereof. This temperature also allows the resulting polymer layer to "bond" with the fibers at the surface of the nonwoven layer, thus allowing good adhesion with the nonwoven. The polymer impermeable layer typically has a thickness of 10-60 μm, preferably 20-40 μm, more preferably about 30 μm. The same polymers can be used for high speed lamination.

[0039] Equipment for carrying out this process is available on the market, such as, for example, the laminating and / or coating systems sold by the company LACOM GmbH.

[0040] The anti-slip coating applied to the other surface is made of, for example, polyurethane, acrylic binder, PVA binder, EVA, rubber, polyolefin or PA. It may also be a pressure-sensitive adhesive. It may also contain fillers, resins, antistatic additives, crosslinkers or any other suitable additives. Spraying can be carried out by hot melt techniques or by spraying the polymer dissolved in water or other solvents. Chemical bonding is also a suitable technique for application of the anti-slip coating, for example using polymer extrusion, knife over roll or any suitable coating system, as known to those skilled in the art.

[0041] The non-slip coating step may be carried out prior to the polymer extrusion of the impermeable layer. The order of these steps is not an essential feature of the process of the present invention.

[0042] The manufacture of a three layer product has been described above. However, the sheet material can have more than three layers, with the additional layers being applied on top of the impermeable surface. The nonwoven sheet material of the present invention can include one or more additional nonwoven sheet materials and / or one or more additional polymer layers on top of the impermeable layer.

[0043] In particular, one or more additional nonwoven sheet materials, whose fibers have a common general orientation, may be applied over the impermeable layer. The one or more additional nonwoven sheet materials may have the same composition as the first nonwoven sheet material, or a different composition to impart additional properties to the final product.

[0044] One or more additional polymer layers can also be applied directly onto the impermeable layer or onto an additional nonwoven material. The one or more additional polymer layers can be any of the polymer materials described above, of any type, e.g., permeable or impermeable. Multiple additional polymer layers, having the same or different properties, can also be applied on top of each other.

[0045] It should be understood that the present invention relates to a nonwoven sheet material having an impermeable layer on one side and an anti-slip coating on the other side, the fibers of which have a common general orientation, and optionally additional nonwoven and / or polymer layers can be applied over the impermeable layer. The additional nonwoven and / or polymer layers can be alternated to impart specific properties to the product.

[0046] For example, as shown in Figure 4, a nonwoven material layer 41 made from a plurality of fibers 44 is covered on one side by an impermeable layer 42 and on the other side by an anti-slip coating 43. A second nonwoven layer 45 is applied over the impermeable layer 42. A second polymer layer 46 is applied over the second nonwoven layer 45.

[0047] Here, the second nonwoven layer is represented with fibers having a common common orientation. The fibers of both nonwoven layers may be of the same or different nature depending on the application.

[0048] The second polymer layer 46 here may be a permeable layer, for example allowing liquid from a spill to pass through. The underlying nonwoven layer 45 may for example facilitate the absorption and distribution of liquid to keep the surface of the product looking dry.

[0049] The second polymer layer may, for example, also have anti-slip properties and / or may have a particular color that aids the user in proper positioning of the sheet material.

[0050] Any combination of additional nonwoven layers and / or additional polymer layers suitable for the particular intended use of the product can be envisioned.

Claims

1. 1. A method for producing a temporary protective nonwoven sheet material having an impermeable layer on one side and an anti-slip coating on the other side, comprising the steps of: carding fibers having a common general orientation along a machine direction to form a web; bonding the fibers into a nonwoven sheet material; applying an anti-slip coating to one surface of the nonwoven sheet material; applying a polymer to a second surface of said nonwoven sheet material to form said impermeable layer; Including, The polymer is applied by laminating or spraying an extruded / molten polymer onto a nonwoven material at a line speed of greater than 25 m / min; Because the method does not include a cross-lapping step applied to the web of fibers prior to bonding, the common general orientation of the fibers is maintained throughout the method. The method is characterized by:

2. 10. The method of claim 1, wherein at least two webs of carded fibers are overlapped and bonded together in said bonding step.

3. 3. The method according to claim 1, wherein the anti-slip coating is applied by hot melt coating.

4. The method according to any one of claims 1 to 3, wherein the impermeable layer is applied by hot melt extrusion.

5. The method of any one of claims 1 to 4, further comprising applying one or more additional nonwoven sheet materials over the impermeable layer.

6. The method of claim 5 further comprising applying one or more polymer layers onto the additional sheet material.

7. The method of any one of claims 1 to 4, further comprising applying one or more polymeric layers onto the impermeable layer.

8. A nonwoven sheet material for temporary protection having an impermeable layer on one side and an anti-slip coating on the other side, characterized in that the fibers of the nonwoven sheet material have a common general orientation along the machine direction.

9. 180g / m ２ 9. The nonwoven sheet material of claim 8 having a weight of:

10. 10. The nonwoven sheet material of any one of claims 8 and 9, comprising at least one blend of fibers.

11. 11. The nonwoven sheet material of claim 10, wherein at least one blend of fibers is selected from the group including a 100% PET fiber blend including bicomponent PET / CoPET bonding fibers having a thickness of 2, 4, 6 or 15 denier, a 100% PLA fiber blend, a biodegradable fiber, a blend of PET structural fibers with other bicomponent fibers, a blend of PET and viscose fibers, or a blend of PET and cellulose fibers.

12. The nonwoven sheet material of any one of claims 8 to 11, comprising one or more additional nonwoven sheet materials and / or one or more additional polymer layers on top of the impermeable layer.

13. 13. An article for protecting a surface made from the nonwoven sheet material according to any one of claims 8 to 12.

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