Apparatus and process for the production of a non-woven fabric

Abstract

Apparatus (1) for producing a nonwoven fabric (150, 170), comprising a spinneret (2) for extruding a plurality of filaments (3); at least one first cooling device (4) arranged below said spinneret (2); a mechanical drawing device (5) arranged below said cooling device, to draw the filaments; a crimping device (6) arranged below said drawing device; a second cooling device (7) arranged below the suction device (6), to cool the filaments; a mechanical distributor (8) arranged below said second cooling device to divert the path of said plurality of filaments; a collecting device (9) of the filaments, arranged below said mechanical distributor (8), said collecting device (9) comprising a collection surface (91) to collect the crimped filaments; a suction element (92) to suction gases below the collection surface (91) of the crimped filaments, and wherein the crimping device (6) comprises a tensioning device (61) and a heating device (62) to crimp the filaments.

Description

FIELD OF INVENTION

[0001] The present invention relates to an apparatus and process for the production of a nonwoven fabric and, in particular, a voluminous or smooth geotextile nonwoven fabric.STATE OF THE ART

[0002] Geotextiles are widely used in civil engineering to build infrastructures such as roads, bridges, railways, dam support works and hydrogeological retaining structures.

[0003] Geotextiles in the form of nonwoven fabric, which exhibit varying degrees of permeability, are known, in that, once placed on the soil or ground of interest, they allow the soil in which geotextiles are placed to be separated, filtered, protected or drained without the need for movement or extraction of soil in which the infrastructure is built. In addition, geotextiles allow the surface on which they are placed to be reinforced, for example by evenly distributing loads on the soil.

[0004] Typically, geotextiles can be produced by an apparatus for the production of filaments by extrusion, which comprises at least one spinning head fed by extruders, cooling devices to cool the extruded filaments, drawing devices to draw the filaments and a device to collect the extruded filaments which form the nonwoven fabric.

[0005] However, geotextiles produced according to the known art have some limitations in terms of mechanical characteristics or are small in volume, i.e., small in thickness.DESCRIPTION OF THE INVENTION

[0006] Therefore, object of the present invention is to make a voluminous nonwoven fabric. Further object of the present invention is a process allowing this nonwoven fabric to be simply and economically produced.

[0007] The present invention achieves these and other objects by means of an apparatus and process according to the attached independent claims. Preferred aspects are set forth in the dependent claims.

[0008] According to an aspect of the present invention, an apparatus for producing a nonwoven fabric comprises: a spinneret for extruding a plurality of filaments; at least one first cooling device arranged below the spinneret; a first mechanical drawing device arranged below the cooling device, to draw the filaments; a crimping device arranged below the mechanical drawing device, which comprises a tensioning device and a heating device to crimp the filaments; a second cooling device arranged below the suction device, to cool the filaments; a mechanical distributor arranged below the second cooling device to divert the path of the plurality of filaments; a filament collecting device arranged below the mechanical distributor, wherein the collecting device comprises a collection surface to collect the crimped filaments; a suction element to suction gases below the collection surface of the crimped filaments.

[0009] The spinneret of the apparatus is configured to extrude filaments by extruding one or more polymers. In a preferred embodiment, the extruded filaments are bi-component filaments typically made by co-extruding two or more polymers. Bi-component filaments comprise two portions or components preferably arranged therein in a side-by-side or core-sheath configuration. According to a possible aspect, in the side-by-side configuration, the contact surface between the two portions has at least one inflection in cross-section, thus giving the section of the contact surface a wavy shape. In the core-sheath configuration, a first portion extruded with a first polymer forms the heart (core) of the extruded filaments while a second portion extruded with a second polymer essentially forms a sheath of the two-component filament.

[0010] The first cooling device allows the filaments downstream of the spinneret to be cooled by a gas flow directed towards the extruded filaments.

[0011] The crimping device allows at least part of the filaments to be crimped. "Crimping" refers to the known-in-the-art condition where the filaments exhibit a plurality of curls and a wavy, irregular pattern such that the length of a crimped filament is significantly less than the length of the filament in the not-crimped condition, that is, in a condition without curls.

[0012] Advantageously, the crimping device allows the filaments to be crimped before being deposited on the collecting device and, as a result, a first voluminous nonwoven fabric can be obtained.

[0013] As described above, the crimping device comprises a tensioning device and a heating device to crimp the filaments.

[0014] Advantageously, the tensioning device allows the filaments to be kept in tension, that is, in a condition in which the filaments do not have waves before being heated by the heating device.

[0015] The second cooling device downstream of the crimping device allows the crimped filaments to be cooled. Such cooling substantially allows any further filament shrinkage to be limited after filament crimping. In other words, the second cooling device stops, or at least slows down, the filament crimping achieved by the crimping device.

[0016] Thanks to the mechanical distributor, the fall path of the crimped filaments is diverted before they are deposited on the collecting device. This allows the spatial distribution of filament deposition on the collection surface of the filament collecting device to be increased. In other words, by means of the mechanical distributor, the crimped filaments falling onto the collection surface can be distributed over a larger surface compared to an apparatus without the mechanical distributor.

[0017] According to an embodiment, the mechanical distributor comprises blades with alternating motion which, upon coming into contact with the filaments, divert the fall path of the filaments onto the collecting device.

[0018] According to an alternative embodiment, the mechanical distributor comprises a movable shelf that allows the fall path of the filaments downstream of the second cooling device to be diverted.

[0019] According to a further embodiment, the mechanical distributor comprises a fixed shelf placed below the second cooling device and a swinging rod at the side of the fixed shelf. Downstream of the cooling device, the filaments come into contact with the fixed shelf, thus changing the direction of filament fall and subsequently coming into contact with the swinging rod, which causes the filaments to swing before they are deposited on the collection surface of the collecting device.

[0020] The filament collecting device arranged below the mechanical distributor allows the crimped filaments to be collected as they fall and allows a first voluminous nonwoven fabric (with a high thickness) to be formed.

[0021] According to a possible aspect, the drawing device comprises rollers.

[0022] The extruded and cooled filaments are at least partially laid on the surface of the rollers, which typically rotate at speeds different from each other, thus diverting their fall path and thereby allowing some of the mechanical characteristics of the filaments to be modified, such as the tenacity, linear density and elongation strength of the extruded filaments. In other words, considering a sectional plane perpendicular to the central axis of one of the rollers, the perimeter of the roller has a substantially circular shape and the filaments are in contact with only part of this circumference, e.g., they are in contact only along an arc of the circumference of the rollers.

[0023] According to a possible aspect, the roller surfaces are treated with hard chrome or with oxides such as aluminum oxide or with Teflon or other treatments.

[0024] According to a possible aspect, the rollers comprise primary rollers and secondary rollers and the secondary rollers are movable relative to the primary rollers.

[0025] Preferably, the primary rollers and the secondary rollers are arranged alternately with each other so that, in use, the filaments meet alternately a primary roller and a secondary roller.

[0026] Typically, the secondary rollers are movable such that they can move between a position of operational disengagement from the filaments, and a second position wherein the filaments are drawn.

[0027] The operational disengagement position is the condition in which the filaments are not in contact with the surface of the secondary rollers. When the secondary rollers are in such a position, the filaments are typically not even in contact with the primary rollers. The drawing position is the condition in which the surface of at least one of the secondary rollers is in contact with at least one portion of the filaments. In that position, typically, the secondary rollers divert the path of the filaments so as to lead them to contact the side surface of the primary rollers as well.

[0028] This movement of the secondary roller allows the draw degree of the filaments and the mechanical properties of the filaments to be adjusted according to the type of desired production of nonwoven fabric.

[0029] In possible embodiments, at least one secondary roller is translatable alternately along one direction by means known in the art.

[0030] According to a possible aspect, the tensioning device forms a depression in the crimping device by means of forced air.

[0031] The tensioning device then allows gases to be suctioned from the crimping device so as to ensure that the filaments leaving the rollers and passing through the crimping device are properly placed under tension in order to ensure that the crimping of the filaments occurs homogeneously by means of the heating device.

[0032] According to a possible aspect, the apparatus comprises at least one needle-felting device downstream of the collecting device, configured to bond the filaments of the first nonwoven fabric.

[0033] In a known way, "bonding" refers to a process in which filaments of the first nonwoven fabric are constrained together in order to give structural stability to the first nonwoven fabric formed.

[0034] According to a possible aspect, the apparatus comprises a thermal treatment device downstream of the needle-felting device, typically adapted to heat the first nonwoven fabric.

[0035] Advantageously, the thermal treatment device allows the shape of the first nonwoven fabric to be stabilized and consolidated. An example of a thermal treatment device might be a chain furnace, for example.

[0036] According to a possible aspect, the apparatus comprises a source configured to arrange at least one layer, preferably at least one second nonwoven fabric, over the first nonwoven fabric.

[0037] The layer deriving from the source can be formed, for example, by filaments or reinforcing fabrics or meshes that can be deposited on the first nonwoven fabric.

[0038] Alternatively, the layer deriving from the source can be derived from filaments subject to drawing by means of a mechanical drawing device, as described above.

[0039] According to a possible aspect, the apparatus comprises a calender, an accumulator and a winder downstream of the needle-felting device.

[0040] The calender may comprise at least two cylinders through which the formed nonwoven fabric passes before being collected by the accumulator and a winder so that it can then be processed according to production requirements.

[0041] Thus, the final nonwoven fabric coincides with the first nonwoven fabric comprising the at least partially crimped filaments, i.e., it essentially comprises a single layer. Alternatively, the final nonwoven fabric can be a composite product comprising a first nonwoven fabric and at least one layer deriving from the source. For the sake of simplicity, we will refer to such a composite product (comprising the first nonwoven fabric) as nonwoven fabric.

[0042] An object of the present invention further relates to a process for the production of a nonwoven fabric, comprising the steps of: a) extruding a plurality of filaments by means of a spinneret; b) cooling said filaments by means of at least one first cooling device arranged below the spinneret; c) drawing the filaments by means of a mechanical drawing device arranged below the cooling device; d) crimping at least part of the filaments by means of a crimping device arranged below the drawing device; e) cooling the crimped filaments by means of a second cooling device arranged below the crimping device; f) operating a mechanical distributor arranged below the second aerodynamic drawing device so as to divert the path of at least part of the filaments; g) depositing the filaments on a collecting device, arranged below the crimping device, along a feed direction in order to form a first nonwoven fabric; h) suctioning gases below the crimping device by means of a suction element arranged below the collecting device and wherein said step d) comprises a step of tensioning and heating the filaments by means of the crimping device.

[0043] During step d), the filaments are crimped and are deposited on the collecting device by a first step of tensioning the filaments leaving the rollers and by a second step of heating the drawn filaments.

[0044] During step f), the filaments previously cooled in step e) are subjected to movement so that the fall path of the filaments is changed. This path can be diverted essentially in any direction other than the fall path substantially perpendicular to the filament collection surface. This allows the surface over which the crimped and cooled filaments are laid to be increased.

[0045] According to a possible aspect, during step d) the filaments are heated to a temperature between 60°C and 150°C and / or during step e) the filaments are cooled to a temperature between 8°C and 15°C.

[0046] According to a possible aspect, in said step d) the filaments are drawn by means of rollers, preferably said rollers have a speed of rotation between 400 meters / minute and 2000 meters / minute.

[0047] The term "speed of rotation" refers here and in the following to the speed tangential to the surface of the rollers.

[0048] Adjusting the speed of rotation of the rollers allows the filament draw to be regulated, and in particular allows the molecular orientation of the filaments to be adjusted during the drawing step by means of the mechanical drawing device.

[0049] According to a possible aspect, at least some of the rollers are heatable to a temperature between 60°C and 150°C, preferably around 80°C. In preferred embodiments, all of the rollers are heatable to a temperature between 60°C and 150°C, excluding the last roller met, in use, by the filaments in their path. The temperature of this last roller is typically between 20°C and 50°C.

[0050] According to a possible aspect, the filaments are at least bi-component filaments comprising a first portion and a second portion, preferably the first portion and the second portion are arranged in a side-by-side or core-sheath configuration.

[0051] Therefore, the bi-component filaments are filaments which comprise two portions consisting of two polymers which have different chemical and / or physical characteristics. Advantageously, the bi-component filaments during step d) can facilitate filament crimping. This is because, for example, the two polymers in the first and second portions may have different thermal expansion coefficients thus leading the filaments to have a high number of curls or to have a particularly pronounced wavy pattern.

[0052] According to a possible aspect, in the case where the configuration of the first portion and second portion is of the side-by-side type, the line of contact between the first and second portions is curved.

[0053] According to a possible aspect, the first and second portions have at least one inflection point along the line of contact.

[0054] An "inflection point" is a condition in which, in the line of contact between the first and the second portions, at least one peak and at least one valley alternate along the line of contact, and in which the peaks face a direction opposite the valleys.

[0055] According to a possible aspect, in the case where the configuration of the first portion and the second portion is of the core-sheath type, the section of the first portion is eccentric relative to the section of the second portion of said bi-component filaments.

[0056] According to a possible aspect, the first portion has a melt flow index different from the melt flow index of the second portion.

[0057] The melt flow index allows the fluid-dynamic behavior of the polymers of the first and second portions of the filaments to be defined. This parameter is particularly relevant during the filament extrusion step in which the appropriate extrusion parameters must be defined depending on the type of nonwoven fabric to be produced. This parameter is also relevant in order to be able to define the filament crimp desired and achievable by the crimping device.

[0058] According to a possible aspect, the melt flow index of the first portion is lower than the melt flow index of the second portion.BRIEF DESCRIPTION OF THE FIGURES

[0059] Hereinafter, referring to the appended figures, exemplary and non-limiting embodiments of the present invention will be described, in which: Figure 1 is a schematic side view of a possible embodiment of an apparatus according to the present invention; Figure 2a is a schematic view of a drawing device of the apparatus in Figure 1, which shows the rotation of the primary and secondary rollers about their relative axes of rotation, Figure 2b is a schematic view of a drawing device of the apparatus in Figure 1, which shows the secondary rollers movable relative to the primary rollers, Figures 3a, 3b are sectional views of two-component filaments in side-by-side or core-sheath configuration as obtainable by the apparatus in Figure 1, Figure 4 is a schematic view of a mechanical distributor according to a possible embodiment of an apparatus according to the present invention, Figure 5 is a schematic view of the mechanical distributor according to a possible embodiment of an apparatus according to the present invention. Figure 6 is a schematic view of an apparatus alternative to the apparatus of Figure 1 for the production of a first nonwoven fabric. DETAILED DESCRIPTION OF THE INVENTION

[0060] An apparatus 1 for the production of a nonwoven fabric comprises a spinneret 2 for extruding a plurality of filaments 3, and at least one first cooling device 4 arranged below the spinneret 2.

[0061] The spinneret is configured, in a known way, to extrude the filaments 3, preferably two-component filaments.

[0062] The extruded filaments can be bi-component filaments comprising a first portion 31 and a second portion 32. Preferably the first portion 31 and the second portion 32 are arranged in a side-by-side or core-sheath configuration.

[0063] According to a preferred aspect, the melt flow index of the first portion 31 is different from the melt flow index of the second portion 32.

[0064] The cooling device 4 is typically configured to direct against the filaments 3 a cooled, or otherwise room-temperature, gas (typically air).

[0065] The apparatus further comprises a mechanical drawing device 5 arranged below the cooling device 4, to draw the filaments.

[0066] The drawing device 5 preferably comprises a plurality of rollers 11 - 15 which are arranged in series and generally have tangential speeds different from each other. Typically, the tangential speeds of the rollers 11 - 15 are progressively increasing, considering the order in which, in use, the rollers 11 - 15 come into contact with the filaments 3 during their fall from the spinneret 2.

[0067] The rollers 11 -15 are rotatable about their own axis of rotation A11 - A15, preferably at a speed between 400 meters / minute and 2000 meters / minute.

[0068] According to an embodiment, at least part of the rollers is configured so that it can be heated, for example by means of an oleodynamic circuit. The heated rollers are configured to have a temperature preferably between 60°C and 150°C when in use. Preferably all the heated rollers are upstream of all the unheated rollers. Specifically, according to a preferred aspect, all the rollers are heated except for the roller immediately upstream of the crimping device 6 (i.e., except for the roller furthest downstream in the path of the filaments 3). This last roller, i.e. the roller 15 in the embodiment shown in the figures, is configured so as to have a temperature between 20°C and 50°C. This can be done by means of a special thermal treatment device (a fluid-dynamic circuit) or, more preferably, such a roller has no heating / cooling means, so that it remains basically at room temperature.

[0069] According to a preferred aspect, the drawing device 5 comprises primary rollers 11, 13, 15 and secondary rollers 12, 14, in which the secondary rollers 12, 14 are movable relative to the primary rollers 11, 13, 15.

[0070] In other words, the primary rollers 11, 13, 15 and the secondary rollers 12, 14 are constrained to the frame of the apparatus (not shown herein in detail) so as to allow a relative movement between the primary and secondary rollers so as to alternatively engage the filaments. The secondary rollers 12, 14 and the primary rollers 11, 13, 15 are preferably arranged alternately with each other so that, in use, the filaments 3 alternately meet a primary roller and a secondary roller.

[0071] The secondary rollers 12, 14 are typically translatable alternately along a curve or, more preferably, a straight line. According to an embodiment, considering a condition of use, the secondary rollers 12, 14 are horizontally movable.

[0072] The apparatus further comprises a crimping device 6 arranged below the drawing device 5.

[0073] The crimping device 6 allows the filaments 3 to be crimped during the fall, downstream of the drawing device 5.

[0074] In particular, the crimping device 6 comprises a tensioning device 61 and a heating device 62.

[0075] The tensioning device 61 is configured so as to accelerate gases along a duct through which the filaments 3 pass, so as to ensure that the filaments 3 leaving the drawing device 5 and passing through the crimping device 6 are tensioned, in order to ensure that the crimping of the filaments occurs homogeneously by means of the heating device 62.

[0076] Such acceleration may be purely aerodynamic (i.e., passive) or it may comprise elements (compressors or the like) adapted to generate a forced air flow within the duct of the tensioning device 61, within which the filaments pass 3.

[0077] The heating device 62 can be configured to heat the filaments 3 by principles known in the art (typically convection and / or radiation).

[0078] The apparatus further comprises a second cooling device 7 arranged below the suction device 6, to cool the filaments.

[0079] Typically, such a second cooling device acts by directing cooled or room-temperature air, or anyway air at a temperature lower than that of the filaments 3, against the filaments themselves.

[0080] By means of the second cooling device, the crimped filaments are cooled so as to stop or at least slow down the filament crimping step. Preferably, the filaments are cooled by means of the second cooling device 7 to a temperature between 8°C and 15°C.

[0081] The apparatus further comprises a mechanical distributor 8 arranged below said second cooling device 7 in order to divert the path of said plurality of filaments, so as to direct them towards a collecting device 9. Specifically, the mechanical distributor 8 allows the crimped filaments 3 to be separated and distributed over the deposition surface 91 of the collecting device 9, in order to form the first voluminous nonwoven fabric 150.

[0082] According to an embodiment, the mechanical distributor 8 comprises a movable shelf 101 on which the filaments 3 leaving the cooling device 7 are laid. The movement of the movable shelf diverts the fall path of the filaments 3, which are deposited on a collecting device 9 comprising a surface 91 on which a first nonwoven fabric 150 is formed.

[0083] According to an alternative embodiment, the mechanical distributor comprises a fixed shelf 102 and a swinging rod 30. The filaments leaving the cooling device 7 are laid on the fixed shelf 102 by deflecting the fall path in the direction of the swinging rod 30, which causes the filaments 3 to swing / vibrate before being deposited on a collection surface 91 of the collecting device 9.

[0084] A further embodiment (not shown in the figures) provides a mechanical distributor comprising alternately moving blades which allow the crimped filaments 3 to be separated and distributed on the deposition surface 91, in order to form the first voluminous nonwoven fabric 150. In general, the mechanical distributor 8 typically comprises a movable element 101, 30 adapted to deflect the filaments 3 in a timevarying way. Preferably, such a movable element moves at a movement frequency of between 100 and 1000 movements (oscillation) / minute.

[0085] The collecting device 9 can take various forms and typically comprises a movable belt. Furthermore, the apparatus typically comprises a suction element 92 to suction gases below the collection surface 91 of the crimped filaments, in order to promote the formation of a first nonwoven fabric 150.

[0086] According to a further aspect, the apparatus comprises at least one source 15, 16 which allows one or more additional layers 160, 160' to be deposited on the first nonwoven fabric 150.

[0087] Such a source 15, 16 is preferably configured to deposit at least one layer 160, 160' on the first nonwoven fabric 150. In particular, the source 15, 16 can be configured to form at least one layer 160, 160' directly on the first nonwoven fabric 150, e.g., by deposition of additional, (possibly crimped), filaments, such as the source 16 shown in the figures. According to a particular aspect, the filaments of the layer 160' can be treated, during their fall, similarly to the filaments 3 of the first nonwoven fabric 150 during the respective fall. Preferably, the filaments of the layer 160' can be treated with a drawing device as described above.

[0088] According to alternative embodiments, the layer 160 may be already formed, so that the source 15, 16 may be a bobbin on which the layer 160' is wound, as the source 15 shown in the figures.

[0089] In alternative embodiments, the source 16, 15 can deposit a different layer 160 on the first nonwoven fabric 150, for example meshes or other reinforcing fabrics which are laid on the first nonwoven fabric 150.

[0090] Although sources 15, 16 different from each other are shown in the embodiment shown in the figures, preferred embodiments typically comprise a single type of source.

[0091] If there are one or more layers 160, 160' deposited on the first nonwoven fabric 150, the final result of the apparatus is a composite nonwoven fabric 170 comprising the first nonwoven fabric 150 and the additional layers deposited thereon. Without these sources, the final nonwoven fabric 170 is formed only by the filaments 3 deposited on the collection surface, i.e. the first nonwoven fabric 150.

[0092] According to a possible embodiment, the apparatus 1 further comprises at least one needle-felting device 18 downstream of the collecting device 9, that is to say downstream of the region where the filaments 3 meet the collecting device 9. The needle-felting device 18 allows the filaments 3 of the first nonwoven fabric 150 to be bonded together, thus enabling the first voluminous nonwoven fabric 150 to be consolidated and the various layers 160, 160', if any, of the composite nonwoven fabric 170 to be consolidated together.

[0093] According to a possible aspect, the apparatus further comprises a thermal treatment device 19 arranged downstream of the region where the filaments 3 meet the collecting device 9 and downstream of the needle-felting device 18, if any. Such a heat treatment device 19 is typically conformed to heat the first nonwoven fabric 150 or the composite nonwoven fabric 170. A preferred embodiment is a chain furnace, although the use of devices known in the art is not excluded.

[0094] In place of the needle-felting device 18 (or together with it, upstream of it), a calender 17, possibly heated, adapted to heat and / or consolidate the filaments, can be provided.

[0095] According to a possible aspect, downstream of the thermal treatment device 19 the apparatus comprises at least one device selected from a calender 20, an accumulator 23 and a winder 24 of the composite nonwoven fabric 170, which can be further treated according to production needs. Preferably, the apparatus comprises the three devices discussed above arranged in series.

[0096] The calender 20, in a known way, allows the first nonwoven fabric 150 or the composite nonwoven fabric 170 to be bonded or, at any rate, consolidated. In a known way, the calender 20 can be heated to promote the bonding of the filaments of the product.

[0097] The accumulator 23 typically has a plurality of rollers, at least one of which is movable, so as to define a path having variable length for the nonwoven fabric 150, 170. Therefore, such a device is typically configured to deliver the product at a constant speed and / or tension downstream of the device itself.

[0098] The winder 24, typically in the form of a bobbin or the like, allows the first nonwoven fabric 150 or composite nonwoven fabric 170 to be wound and stored.

[0099] In use, a plurality of filaments 3 is extruded from the spinneret 2.

[0100] Following the extrusion step, the extruded filaments are cooled by means of the cooling device 7 arranged below the spinneret 2.

[0101] After the cooling step, the filaments 3 are drawn by means of the drawing device 5 which is arranged below the cooling device 7.

[0102] As described above, the drawing device 5 typically comprises primary rollers 11, 13, 15 and secondary rollers 12, 14 in which the secondary rollers are movable relative to the primary rollers.

[0103] At first, at the initial operating step of the spinneret 2, the secondary rollers are typically arranged in the disengaged condition to allow the filaments 3 to pass between the rollers 11 - 15. Next, the secondary rollers are brought to the drawing position, so as to engage the filaments and cause them to be drawn.

[0104] The filaments passing around the rollers alternately meet the first and second secondary rollers. In other words, the filaments are laid alternately on a surface portion of a primary roller and then are laid on a surface portion of a secondary roller. Typically, the filaments 3 exhibit a basically S-shaped pattern in the transition from a primary roller to a secondary roller.

[0105] As discussed, according to a possible aspect, at least part of the rollers are heatable, preferably between 60°C and 150°C, so as to affect the temperature of the filaments 3. The last roller to meet the filaments is preferably unheated, at a temperature between 20°C and 50°C.

[0106] After the drawing step, at least part of the filaments 3 is crimped by means of the crimping device 6 which is arranged below the drawing device 5. Specifically, the filaments are tensioned by the tensioning device 61 and heated by the heating device 62. As discussed, bi-component filaments are preferred because, at this stage, the different behavior (elongation or shrinkage) of the two portions favors the formation of crimped filaments.

[0107] Preferably, the filaments are heated by means of the heating device 62 to a temperature between 60°C and 150°C.

[0108] Next, the crimped filaments are cooled, preferably to a temperature between 8°C and 15° by the cooling device 7.

[0109] Then, the crimped and cooled filaments 3 are diverted in their fall path by the mechanical distributor 8 in order to increase the surface where the filaments 3 are deposited on the deposition surface 91 of the collecting device to form the first nonwoven fabric 150.

[0110] Below the collecting device 9, the suction element 92 suctions air so as not to disperse the filaments deposited on the deposition surface 91 and ensure the proper formation of the first nonwoven fabric 150.

[0111] Subsequently, the first nonwoven fabric 150 can undergo different treatments.

[0112] For example, a composite nonwoven fabric 170, comprising the first nonwoven fabric 150 and additional layers 160, 160' deposited on the first nonwoven fabric 150 by means of one or more sources 15, 16, can be formed.

[0113] As an alternative, the final nonwoven fabric comprises the first nonwoven fabric 150 which comprises the at least partially crimped filaments 3, i.e. it essentially comprises a single layer.

[0114] Both the first nonwoven fabric 150 and the composite nonwoven fabric 170 can be calendered, by means of the calender 17, and / or needle-felted by means of the needle-felting device 18 and possibly heated by means of the heating device 19.

[0115] The first nonwoven fabric 150 or the composite nonwoven fabric 170 is then collected, possibly being previously further consolidated by the calender 20. The accumulator 23 can adjust the speed / tension of the first nonwoven fabric 150 or the composite nonwoven fabric 170 before they are wound.

Claims

1. Apparatus (1) for producing a nonwoven fabric (150, 170), comprising: - a spinneret (2) for extruding a plurality of filaments (3); - at least one first cooling device (4) arranged below said spinneret (2); - a mechanical drawing device (5) arranged below said cooling device, to draw the filaments; - a crimping device (6) arranged below said mechanical drawing device (5); - a second cooling device (7) arranged below the suction device (6), to cool the filaments; - a mechanical distributor (8) arranged below said second cooling device to divert the path of said plurality of filaments; - a collecting device (9) to collect the filaments, arranged below said mechanical distributor (8), said collecting device (9) comprising a collection surface (91) to collect the crimped filaments; - a suction element (92) to suction gases below the collection surface (91) of the crimped filaments, the crimping device (6) comprising a tensioning device (61) and a heating device (62) to crimp the filaments.

2. Apparatus according to claim 1, wherein the drawing device (5) comprises rollers.

3. Apparatus according to claim 2, wherein said rollers comprise primary rollers (11, 13, 15) and secondary rollers (12, 14), said secondary rollers being movable relative to said primary rollers.

4. Apparatus according to one of the preceding claims, wherein at least part of the rollers can be heated to a temperature between 60°C and 150°C, preferably all of the rollers can be heated to a temperature between 60° C and 150°C, excluding the last roller met by the filaments in their path, during use.

5. Apparatus according to any one of the preceding claims, wherein said tensioning device (61) forms a depression in the crimping device (6) by forced air.

6. Apparatus according to any one of the preceding claims, comprising at least one needle-felting device (18) downstream of the collecting device (9), configured to bond the filaments of the first nonwoven fabric (150).

7. Apparatus according to claim 6, comprising a stabilizing thermal treatment device (19) downstream of the needle-felting device.

8. Apparatus according to any one of the preceding claims, comprising a source (15, 16) configured to arrange at least one layer (160, 160'), preferably at least one second nonwoven fabric, over the first nonwoven fabric (150).

9. Process for producing a nonwoven fabric (150.170) comprising the steps of: a) extruding a plurality of filaments (3) by means of a spinneret (2); b) cooling said filaments (3) by means of at least one first cooling device (4) arranged below the spinneret; c) drawing said filaments (3) by means of a mechanical drawing device (5) arranged below said cooling device, d) crimping at least part of said filaments (3) by means of a crimping device (6) arranged below the drawing device (5); e) cooling said crimped filaments by means of a second cooling device (7) arranged below the crimping device (6); f) operating a mechanical distributor (8) arranged below said crimping device (6) so as to divert the path of at least part of crimped and cooled filaments; g) depositing said filaments on a collecting device (9), arranged below said crimping device (6), along a feed direction (D) in order to form a first nonwoven fabric (150); h) suctioning gases below said crimping device (6) by means of a suction element (92) arranged below said collecting device (9); wherein said step d) comprises a step of tensioning and heating said filaments by means of said crimping device (6).

10. Process according to claim 9, wherein in said step d) the filaments are heated to a temperature between 60°C and 150°C and / or in said step e) the filaments are cooled to a temperature between 8°C and 15°C.

11. Process according to claim 9 or 10, wherein in said step d) the filaments are drawn by means of rollers, preferably said rollers have a tangential speed of rotation between 400 meters / minute and 2000 meters / minute.

12. Process according to one of preceding claims 9 to 11, wherein at least part of the rollers is heated to a temperature between 60°C and 150°C, preferably all the rollers are heated to 60°C and 150°C excluding the last roller met by the filaments in their path, which is preferably set at a temperature between 20°C and 50°C.

13. Process according to any one of preceding claims 9 to 12, wherein said filaments are at least bi-component filaments comprising a first portion (31) and a second portion (32), preferably the first portion (31) and the second portion (32) are arranged in a side-by-side or core-sheath configuration.

14. Process according to claim 13, wherein the melt flow index of the first portion (31) is different from the melt flow index of the second portion (32).

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