Non-woven web with fibers

Abstract

A conveyor system comprising a first conveyor for drying a non-woven fiber structure, including a permeable belt and a pulley for guiding the belt. The pulley is situated at the discharge point of the first conveyor. A second conveyor is present for receiving the non-woven fiber structure discharged from the first conveyor. The conveyor system further comprises means to separate the non-woven fiber structure from the belt so that the non-woven fiber structure separates from the belt of the first conveyor before reaching the zone where the belt contacts the pulley at the discharge point.

Description

Non-woven web with fibersField of the invention

[0001] The invention relates to the field of non-woven webs. More specifically it relates to production methods of non-woven webs using fibers.Background of the invention

[0002] In general, when processing staple fibers including natural, synthetic, glass, carbon and metal fibers, glue is used to hold the fiber structure together during processing. In this way after drying, the formed web can be rolled, cut and further processed so as to form a web, with the required strength. The glue is part of the final product. In the particular case of non-woven webs with metal fibers, the glue has to be removed before the necessary step of sintering, in order to enable the diffusion process.

[0003] For stainless steel, nickel fibers and other metals, for example, the glue can be removed by burning it away at 400°C - 500°C in ambient air. A harmful consequence is that the fibers may be severely oxidized. In order to reduce oxidation, a reducing hydrogen atmosphere can be used to carry out the sintering. However this solution is not applicable to all metals due to hydrogen brittleness, which results in fiber products that are too brittle, or even in pulverization of the fibers.

[0004] It would be desirable to provide a web of non-woven fibers with no danger of oxidation or brittleness, and with low amounts of residue.Summary of the invention

[0005] It is an object of embodiments of the present invention to provide a wet-lay production process and system which advantageously does not require glues or other binders that leave a residue after sintering. It is a further object to provide a web of non-woven metal fibers with no ash residue from burning the binder, with low or no oxidation or brittleness due to hydrogen.

[0006] In a first aspect, the present invention provides a conveyor system comprising a first conveyor for drying a non-woven fiber structure, including a permeable belt and a pulley for guiding the belt. The non-woven fiber structure is transferred or discharged from the first conveyor at a discharge point. The pulley is situated at the discharge point of the first conveyor. A second conveyor is present for receiving the non-woven fiber structure discharged from the first conveyor. The conveyor system further comprises means, e.g. a slider or a rolling shaft, to separate the non-woven fiber structure from the belt so that the non-woven fiber structureseparates from the belt of the first conveyor before reaching the zone where the belt contacts the pulley at the discharge point. The first conveyor and the second conveyor are driven at a predetermined speed, and the means to separate the structure may comprise the predetermined speed of the first and second conveyors.

[0007] It is an advantage of embodiments of the present invention that no binder such as glue is required to form a mat. It is a further advantage that entanglement of the fibers with the pulley and belt is reduced or avoided.

[0008] In preferred embodiments, the means to separate the structure comprises a slider or rolling shaft on or above the belt of the first conveyor, upstream the zone where the belt contacts the pulley.

[0009] It is an advantage of embodiments of the present invention that good lifting is provided even if the first and second conveyors are horizontal, even if both conveyors the belt surfaces in contact with the fiber structure are coplanar.

[0010] In particular and best embodiments, the means is a rolling shaft configured for turning, such that the tangential speed of its surface is higher than the speed of the belt of the first conveyor. Rolling shaft typically can bring high precision, offering good axial and radial rigidity. In addition, roller or rolling shaft are generally relatively easy to maintain due to their design, allowing for easy replacement of rolling elements and extending bearing life.[Oil] It is an advantage of embodiments of the present invention thatgood lifting is provided even if the first and second conveyors are horizontal, even if both conveyors the belt surfaces in contact with the fiber structure are coplanar.

[0012] In some embodiments, the means to separate the structure comprises positioning at least the first conveyor forming a slope.

[0013] It is an advantage of embodiments of the present invention that the take- off distance can be controlled by controlling the speed of the conveyor belts, the distance between the belts and the slope, without any other further device. For example, the belt may have an inclination of 10 degrees or higher than 10 degrees, for example 15 degrees, for example 20 degrees. The inclination and relative speeds of the belts are such that the web is fully lifted from the conveyor belt before reaching the pulley.

[0014] In some embodiments, the pulley of the first conveyor is placed underneath the plane defined by the belt of the second conveyor. Alternatively, in some embodiments, the planedefined by the belt of the first converyor is in the same horizontal plane of the plane defined by the belt of the second conveyor.

[0015] It is an advantage of embodiments of the present invention that controlling the speed allows controlling the take- off of the structure. It is a further advantage that the hanging point can be accurately controlled, if the first conveyor forms a slope.

[0016] In some embodiments, the means to separate the structure comprises an aspirator for lifting the structure from the first conveyor by sucking.

[0017] It is an advantage of embodiments of the present invention that the aspirator can remove remaining moisture during transfer.

[0018] In a further aspect, a method of transferring a structure made of non-woven stiff fibers between a first and second conveyors for forming a fiber mat is provided. The method comprises providing a structure made of non-woven stiff fibers moistened or wetted with water on the first conveyor comprising a permeable belt with a pulley, subsequently drying the structure through the permeable belt, subsequently lifting the structure from the first belt on an area of the belt removed from the zone where the belt contacts the pulley of the first conveyor, and finally depositing the structure on the second conveyor.

[0019] It is an advantage of embodiments of the present invention that the belt can be used to dry the fibers without risk that the fibers entangle in the belt and pulley thereof. It is a further advantage that the obtained structure can be sintered in vacuum to obtain a mat, with no need of burning the binder or sintering in hydrogen atmosphere.

[0020] In some embodiments, the structure made of non-woven fibers moistened or wetted with water is made from a suspension of mixing stiff fibers with water.

[0021] It is an advantage of embodiments of the present invention that costs and materials can be reduced by avoiding using glue. It is a further advantage that the mat obtained at the end of the process does not have residue from the glue after further treatment such as heating treatment and / or sintering, thus improving purity of the mat.

[0022] In a further aspect, a non- woven fiber mat porous structure for porous transport layer for electrolyzer, for isolation, filtration or separation of chemicals, the mat being made of stiff fibers comprising zero binder residue and zero binder ash.

[0023] It is an advantage of embodiments of the present invention that the mat does not need additional step for removing the glue. It is an additional advantage that the obtained mat is clean with no ash residue from glue.

[0024] The fiber mat of embodiments of the present invention may be obtained by the method of the first aspect of the present invention.

[0025] In some embodiments, the mat comprises or consists of metal fibers, e.g. stainless steel, nickel and / or titanium fibers.

[0026] In some embodiments, the stiffness range of the stiff fibers is from 4xl0-5to 3xl0-1Nmm2. In some embodiments, the length / diameter ratio is in a range from 250 to 3000.

[0027] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

[0028] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.Brief description of the drawings

[0029] FIG 1 illustrates a conveyor system showing a part of two conveyor belts, in particular for transferring a web between two belts forming a slope.

[0030] FIG 2 illustrates a conveyor system with a part of two conveyor belts, in particular for transferring a web using a slider.

[0031] FIG 3 illustrates a conveyor system with a part of two conveyor belts, in particular for transferring a web using an air system for absorbing and lifting the web.

[0032] FIG 4 is a scheme of a method in accordance with embodiments of the present invention.

[0033] The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

[0034] Any reference signs in the claims shall not be construed as limiting the scope.

[0035] In the different drawings, the same reference signs refer to the same or analogous elements.Detailed description of illustrative embodiments

[0036] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0037] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0038] Moreover, the terms top, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0039] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. The term "comprising" therefore covers the situation where only the stated features are present and the situation where these features and one or more other features are present. Thus, the scope of the expression "a device comprising means A and B" should not be interpreted as being limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0040] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0041] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure andaiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0042] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0043] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0044] Where in embodiments of the present invention reference is made to "binder", reference is made to a substance prepared to provide long term adherence of bodies. For example, while water can be used to agglomerate fibers, it is not considered a binder because water does not provide long term adherence by itself. Thus, glue or other adhesives are considered binders. Notably, binder leaves residue if burned or decomposed in an atmosphere without oxygen at high temperatures. If binder is decomposed at high temperature in an atmosphere with oxygen, this would result in oxidized fibers. If sintered in reducing atmosphere, e.g. in hydrogen, in some cases (e.g. titanium fiber web), this result in brittle fibers.

[0045] The present invention relates to processing of non-woven webs, specifically made of metal fibers. Due to the requirement of removal of binder, the properties of the web are usually worsened due to oxidation or embrittlement as a result from burning the binder away and the solution of sintering in hydrogen atmosphere cannot be used for some metals such as titanium due to hydrogen embrittlement. The inventors found that it is possible to form a web by wet-lay process, without using binders. Since no glue or similar binders are used, there is noresidue after sintering. This is enabled by the system and process in accordance with embodiments of the present invention.

[0046] Within an industrial processing of non-woven webs, a wet web is provided on a belt conveyor for transfer to a furnace. The wet web needs to dry while taking it to the sintering stage. This requires also transfer from a first conveyor to a second conveyor for feeding it to a furnace. If no glue or similar binder is used, the transfer proves difficult since the fibers become entangled during the transfer between belts, causing the web to break.

[0047] A common type of transfer is the end-to-end transfer. The product moves from the outfeed end, or discharge zone, of one conveyor to the infeed end of the following belt. These zones are referred to as transfer zones. Thus, a transfer zone is the zone of the belt where material is received or leaves the belt. Usually both ends are adjacent and coplanar for a smooth transition, and sometimes the outfeed end is set slightly higher than the infeed end, so the web falls from the first conveyor belt to the next.

[0048] It is believed that entanglement and tear occur when the fibers stick into the belt. Since fibers are metallic, they are usually stiff enough to enter the material of the belt. A possible explanation is that fibers sticking into the belt actually reach the other side of the belt, which is in direct contact with the pulley. When the mat reaches the end of the belt conveyor where the pulley drives the belt, the fibers then become pressed by the pulley while the rest of the mat, at the other side of the belt, becomes separated. Since the mat is being transferred while fibers thereof are trapped by the pulley and the belt, the mat tears. Using a strong material for the belt, one that does not allow introduction of the fibers, is in principle possible. However the belt requires porosity since the web needs to dry up. Use of additional porous layers between the wet web and the belt (such as paper) is not a practical solution in industrial processing.

[0049] The inventors found that lifting the web before the usual discharge zone of the belt conveyor solves the issue of web tearing. The take-off of the web is performed before the web reaches the point of contact between the pulley of the conveyor and the belt. The present invention provides a system configured so that the transfer zone of the first conveyor belt is situated away from the contact between the pulley and the belt. This way, since the mat is lifted before the fibers penetrating the belt reach the pulley, the mat is not pulled by trapped fibers. For example, the fibers may not be stuck or trapped between the material of the beltand the pulley when transfer takes place. In fact, the system is configured so that no wheel or pulley may contact stuck fibers.

[0050] In a first aspect, the present invention provides a conveyor system that allows processing the fibers following a wet-lay method, for drying and transferring the web through a belt conveyor to a furnace. The system includes a first conveyor with a permeable belt, allowing the water of the web to drip while transporting the wet web, thus drying it. The conveyor system enables this process with no risk of entangling, thus keeping the integrity of the web.

[0051] The conveyor system is configured to lift the web from the belt of a first conveyor, before reaching the pulley, and transfer it to another conveyor for further treatments, e.g., sintering. The take-off is enabled by implementing a raising force on the system.

[0052] In some embodiments of the present invention, the belts are configured to provide a predetermined speed of the belts which can combine with the raising force, countering gravity. The system allows lifting the web from the belt in motion, at a predetermined distance from the pulley.

[0053] In some embodiments, the raising force may originate from the relative slope of the belts, so the continuous web forms a catenary shape allowing a transfer from one belt to another. FIG 1 shows a portion of a first conveyor 100 for transferring a web W to a second conveyor 110, in accordance with embodiments of the present invention. The web may proceed in the direction of the block arrows, e.g., from a webber and the second conveyor may send it to a following stage of processing, e.g., to a furnace for sintering or the like.

[0054] The first and second conveyors are inclined with respect to each other, specifically there is an inclination between the contact surface of the belt 101 of the first conveyor relative to the receiving surface of the second conveyor, so that the web W is lifted from the belt 101 before the web reaches the pulley 102 of the first conveyor 100, and the web is transferred from the first to the second conveyors of the web. The receiving surface of one of the conveyors may be inclined. In the example of the figure, the contact surface 103 of the belt 101 of the first conveyor 100 is inclined with an angle A, while the receiving surface 113 of the other conveyor may be horizontal. The angle A between the first conveyor and the horizontal (reference level) may be for example 10 degrees or more, for example 15 degrees or more, for example 20 degrees or more. Alternatively, both the surfaces of both conveyors 100, 110 may be inclined relative to the horizontal.

[0055] In some embodiments, the predetermined speed at which the belts move may also be chosen so that there is an inertia that allows the desired transfer. In other words, the inertia and the inclination allow to control the region where the web is lifted, the region being away from the pulley, so the web does not reach the pulley. The speed to be implemented depends on several factors (angle between the belts, distance D between conveyors, density of the web which influences its weight, etc.) and it can be experimentally determined.

[0056] In some embodiments, the raising force may stem from an interposed slider between the belt and web upstream from the pulley. FIG 2 shows also a portion of a first and second conveyors 200, 210, for transferring the web W between different treatment units. The conveyor surfaces in contact with the web W, in this case, are horizontal, but they may also present a slope as in FIG 1. However, in FIG 2 they are shown as horizontal, and additionally also coplanar belts, the present invention not being limited thereto.

[0057] On top of the belt 201 of the first conveyor 200, upstream the pulley 202, a slider S is included. The slider S physically lifts the web W, i. e. the web W going over slider S, when the belt 201 moves it towards the end comprising the pulley 202. The slider S wedges between belt 201 and web W. In some embodiments of the present invention, the slider S is a shaft, e.g. a rotatable cylindrical shaft. For example the rolling shaft may be configured to rotate around its axis (as shown by the rotating arrow), improving the lift. In some embodiments, the tangential speed at the shaft surface is higher than the speed of the belt 201 of the first conveyor belt. This reduces chances of the web being caught between the shaft and belt, thus reducing chances of clogging.

[0058] Once the web is lifted from the belt of the first conveyor, it is transferred to the following conveyor, which pulls the web due to the speed imparted by the second conveyor and does not allow the web to fall over the pulley of the first conveyor. In some embodiments the inertial force provided by the speed of the conveyors also contributes to the web transition between the conveyors without reaching the pulley of the first conveyor.

[0059] In some embodiments, the system may include an air system 300 which lifts the web from the belt, thus providing the raising force. For example, FIG 3 shows two conveyors 200, 210 as in FIG 2, where the air system 301 is a suction belt overlapping both conveyors. The suction belt is arranged so that the web W is lifted from the belt 201 of the first conveyor 200 before reaching the pulley 202. The suction belt provides a vacuum effect on a predetermined area 30 thereof. The web W is pushed against gravity while being transported to the secondconveyor 210. Once the web leaves the area 301 with the vacuum effect, it drops over the second conveyor 210.

[0060] The suction belt also may improve drying of the web.

[0061] In embodiments of the present invention, the suction belt moves in the same direction of the web at the contacting plane. In some embodiments, preferably the suction belt and the conveyor belt move at the same speed.

[0062] In some embodiments, the system may be arranged so the pulley of the second conveyor is situated above the pulley of the first conveyor, at a predetermined elevation h (shown in e.g. FIG 1). The receiving surfaces of the conveyors may be horizontal but the surface of the belt of the first conveyor may be underneath the plane defined by the receiving surface of the second conveyor. For example, in an inclined system, the plane defined by the receiving surface of the second conveyor may intersect the receiving surface of the belt of the first conveyor.

[0063] The system may include different combinations of features allowing transfer, e.g. a rolling shaft combined with the slope, or with the sucking belt, for example.

[0064] In a second aspect, the present invention provides a method of transferring a nonwoven fiber web from the first to the second conveyors to allow drying the web before transfer to a sintering furnace. The method comprises providing a structure made of moistened or wetted non-woven stiff fibers on a first conveyor. The structure may be a wet-lay web for example. The first conveyor includes a permeable belt with a pulley, allowing drying the wet- lay web.

[0065] The method also comprises lifting the wet-lay web before reaching the pulley of the belt, thus avoiding that any fiber penetrating the permeable material of the belt becomes stuck between the pulley and the belt. This is obtained by providing a lifting force.

[0066] In some embodiments, the web is laid out so that the transfer of the first edge of the web can be done with additional assistance, for example by holding up the web above the belt close to the pulley to avoid that the web falls in the zone of the belt in contact with the pulley. Then the belts may start, and their speed may be controlled so that the web keeps the inertia, and the transfer takes place before the zone of the belt in contact with the pulley.

[0067] FIG 4 is a schematic method of the present invention, comprising providing S40 a structure made of non-woven stiff fiber, which are moistened or wetted with water. This may comprise mixing S47 wetted or moistened fibers together. The structure may be a wet fiberweb. In some embodiments the fibers comprise metal fibers, e.g. steel, nickel and / or titanium fibers. This is not the only possibility, and the fibers may comprise e.g. oxides, ceramics, polymers or the like. For example, a mix with metal or oxides or ceramics in powder or fiber form can be provided. It is also possible to mix with metal powders or polymer fibers to have a hybrid structure.

[0068] The structure is provided on the first conveyor, which includes a permeable belt with a pulley. The method comprises drying S41 the structure by allowing water transfer through the belt. The structure is lifted S42 from the first belt, so that the web separates from the belt before the belt reaches the pulley that drives it. Since the belt is permeable to allow drying, the relatively stiff fibers penetrating the belt do not reach the pulley, so they do not become trapped between pulley and belt, thus preventing tearing of the structure.

[0069] Then, the structure is deposited S43 on the second conveyor and sent to subsequent units, e.g., a sintering furnace or the like.

[0070] In some embodiments, providing the lifting force comprises providing a horizontal tension on a hanging web between the two conveyors, by providing S44 an inclination between the contact surface of the belt of the first conveyor relative to the receiving surface of the second conveyor so that the web separates from the belt at the desired position. The angle may be for example 10 degrees or more, for example 15 degrees or more, for example 20 degrees or more.

[0071] The method may comprise adjusting the speed of the conveyors, causing a corresponding change on the inertial force. The speed together with the inclination contributes to the lifting of the web before reaching the pulley. The distance between the two conveyors may also be taken into account for the adjustment of inclination and / or speed.

[0072] In some embodiments, the method may comprise providing a relative inclination so that the plane formed by the receiving surface of the second conveyor intersects the receiving surface of the belt if the first conveyor upstream from the pulley.

[0073] In some embodiments, the method may comprise placing the belt of the first conveyor so that its pulley remains underneath the plane defined by the belt of the second conveyor. This also includes two parallel belts, where the receiving belt is above and overlapping the first belt, so the first belt does not reach the pulley.

[0074] In some embodiments, the method comprises using S45 a slider upstream from the pulley as explained with reference to the previous aspect. Alternatively or additionally, themethod may comprise using S46 an air system to lift the web, as explained with reference to the previous aspect.

[0075] In some embodiments, the method may comprise transferring the web for sintering, thus providing a non-woven fiber mat. Since no binder is used, there is no ash residue or the like left on the mat. Non-woven mats made of or including some important fiber materials, such as titanium fiber, can be obtained from a sintered web. Since the present invention allows providing a mat wherein no binder is used, there is no need to submit the fibers to thermal treatments that would embrittle or pulverize them. For some materials, e.g. nickel fibers, the lack of binder may allow applying shorter heating time during sintering a web. It may even allow a wider range of sintering processes available, for example it may allow sintering in an atmosphere without inert or reducing gas.

[0076] In a further aspect, a non-woven fiber mat is provided. The mat may be produced using a conveyor system of the first aspect of the present invention. The mat is produced following a method of the present invention, using no binder. As such, the mat of the present invention does not include ash residue.

[0077] The fibers of the mat may have a stiffness of 4xl0-5to 3xl0-1Nmm2which depend on many factors, such as shape (fibers with round cross section, or fibers with triangular cross section). A general trend is that the larger the cross- section area, the higher the stiffness. The equivalent diameter of the fibers in these studies vary between 5 to 50 pm. If the cross-section of the fibers is not in round shape, e.g. in irregular shape, the equivalent diameter is the diameter calculated from a circular area having the same area of the irregular shape crosssection area.

[0078] In fibers with equivalent round cross-section, stiffness may vary along 4xl0-5to 7xl0-2Nmm2, e.g., 2xl0-3to 4xl0-2Nmm2, depending on the type of material (for example, pure Ni). The value for fiber with triangular cross-section (when measuring direction parallel to the base of triangular shape) varies between 6xl0-5to 9xl0-2Nmm2. For a fiber with triangular section, and when measuring in a direction perpendicular to the base of triangular shape, the stiffness value varies between 2.7xl0-4to 3xl0-1Nmm2. This relatively high stiffness, combined with the typical length of the non-woven fibers, cause usually that the fibers penetrate the permeable belt while drying. The present invention allows solving the problems linked to this (e.g., tearing of the non-woven fiber structure) without using a binder during production.

[0079] In embodiments of the present invention, the web structure made of non-woven fibers moistened or wetted with water is preferably made from fibers having a desired length / diameter (L / D) ratio. In general, the ratio L / D may be from 250 to 3000.

[0080] In any case, the amount of binder residue is null after sintering, since no binder is used.

Claims

Claims1. A conveyor system comprising:-a first conveyor for drying a non-woven fiber structure, comprising a permeable belt and a pulley for guiding the belt, the pulley being at the discharge point of the first conveyor,-a second conveyor for receiving the non-woven fiber structure discharged from the first conveyor, wherein the conveyor system further comprises a slider or a rolling shaft to separate the non-woven fiber structure from the belt so that the non-woven fiber structure separates from the belt of the first conveyor before reaching the zone where the belt contacts the pulley at the discharge point, wherein said slider or rolling shaft is on or above the belt of the first conveyor upstream the zone where the belt contacts the pulley.

2. The conveyor system of the previous claim wherein the rolling shaft is configured for turning such that the tangential speed of its surface is higher than the speed of the belt of the first conveyor.

3. The conveyor system of any one of the previous claims wherein the first conveyor is positioned to form a slope.

4. The conveyor system of any one of the previousclaims wherein the pulley of the first conveyor is placed underneath the plane defined by the belt of the second conveyor.

5. The conveyor system of any one of the previous claims wherein the plane defined by the belt of the first converyor is in the same horizontal plane of the plane defined by the belt of the second conveyor.

6. A method of transferring a structure made of non-woven fibers between a first and second conveyors for forming a fiber mat, the method comprising:- providing a structure made of non-woven fibers moistened or wetted with water on the first conveyor comprising a permeable belt with a pulley,- drying the structure through the permeable belt,- lifting the structure by going over a slider or a rolling shaft from the first belt on an area of the belt removed from the zone where the belt contacts the pulley of the first conveyor,- depositing the structure on the second conveyor.

7. The method of the previous claim wherein the structure made of non-woven fibers moistened or wetted with water is made from a suspension of mixing fibers with water.

8. A non- woven fiber mat porous structure for porous transport layer for electrolyzer, for isolation, filtration or separation of chemicals, the mat being made of fibers comprising zero binder residue and zero binder ash.

9. The fiber mat of the previous claim obtained by the method of any one of claims 6 or 7.

10. The fiber mat of any one of claims 8 or 9 comprising or consisting of metal fibers, e.g. stainless steel, nickel and / or titanium fibers.

11. The fiber mat of any one of claims 8 to 10 wherein the stiffness range of the fibers is from 4xl0-5to 3xl0-1Nmm2.

12. The fiber mat of any one of claims 8 to 11 wherein the length / diameter ratio is in a range from 250 to 3000.

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