Spinneret for multi-rotor coaxial spunbond and / or melt-blown type plant

Abstract

To provide a spinneret for a multi-rotor coaxial spunbond and / or melt-blown plant.SOLUTION: A spinneret 1 includes: a plurality of acceleration ducts 2, each of which extends along its own supply axis 2a crossing the main plane 1b and each of which is adapted to supply a respective polymer filament along the supply axis; a plate 7 having first holes 70 accommodating the acceleration ducts, and second holes 71 that are spaced apart from the first holes and allow passage of air or gas; and a mask 8 that is adjacent to the plate along a vertical axis 1a, is centered on the first holes, is fluidly connected to the second holes, and accommodates a part of the acceleration ducts while having a plurality of third holes 80 through which air or gas passes, wherein the second holes are in a number greater than 4, are distributed around at least a part of the first holes, and have their centers located along a circumference 7a that develops around the first holes in parallel with the main plane without touching other first holes.SELECTED DRAWING: Figure 1a

Description

[Technical Field]

[0001] The present invention relates to a spinneret for a multi-row coaxial spunbond and / or meltblown type plant of the type specified in the preamble of the first claim.

[0002] In particular, the present invention relates to the end of a multi-row coaxial spunbond and / or meltblown type plant adapted to allow distribution of a polymerizing fluid at the output from the plant in the form of extruded polymerizing filaments to obtain a nonwoven fabric.

[0003] As is known, nonwoven fabrics, or NWFs (non-woven fabrics), are industrial products similar to textiles, but realized by processes other than weaving and knitting. Thus, in nonwoven fabrics, the fibers have a random pattern without any discernible ordered structure, while in textiles, the fibers have two predominant, orthogonal directions, usually called weft and warp. Summary of the Invention

[0004] Currently, several products, including NWFs, are manufactured depending on the manufacturing techniques used, primarily related to the application in which the product itself will be utilized.

[0005] In particular, a distinction is made between high quality NWFs for hygiene products and low quality NWFs used especially for geotexing.

[0006] From a technical point of view, nonwoven fabrics can be basically divided into spunlace, spunbond, and multi-row coaxial or cusp meltblown fabrics.

[0007] Spunlace fabrics undergo a process that gives them isotropic resistance. Thanks to this property, the possibility of producing them in different materials (viscose, polyester, cotton, polyamide, microfiber, etc.), the two possible finishes (smooth or porous), and the many smooth or printed colors, spunlace is suitable for both the hygiene sector and the automotive, beauty, industrial, or single-use sectors.

[0008] Spunbond, typically made from polypropylene, is a nonwoven fabric that finds multiple applications in agriculture, hygiene, construction, furniture, mattresses, and other related fields. With appropriate treatments, it is possible to create a range of highly specialized products for each field: fluorescent, soft calendared, anti-mite, fire-resistant, anti-bacterial, anti-static, UV-resistant, and more. Numerous finishes are also applicable to spunbond, including printing, lamination, flexographically printed laminates, and self-adhesive.

[0009] A spunbond nonwoven production facility basically includes at least one inlet line for polymeric material, a polymer extrusion head, a polymer distributor or breaker plate, and a spinneret adapted to produce the actual spunbond yarns that are deposited on a conveyor belt.

[0010] The aforementioned elements are each appropriately positioned adjacent to one another to allow for polymer processing and distribution of the NWF spunbond.

[0011] More specifically, the polymer inside the feed line is forced towards the extrusion head under pressure and at elevated temperatures, typically above 200° C. At this point, pressure control is typically performed, for example using a pressure switch, to ensure the continuity of the output yarn and the accuracy of the deposition process.

[0012] The extrusion head distributes the polymer along a distribution surface through which the molten polymer reaches the distributor. Between the distributor or breaker plate and the extrusion head there is a filter made of steel sheet with a thickness usually varying between 0.8 mm and 1.6 mm, containing a fine mesh with a nominal size comprised, for example, between 20 μm and 110 μm. Essentially, the filter is therefore a stretched net.

[0013] After passing through the filter interior, the molten polymer enters a distributor, where it is directed to a spinneret that extrudes the polymer into filaments that make up the NWF spunbond. Specifically, the filter has the purpose of blocking any incompletely melted or in some cases larger particles or polymer pigments that may enter the spinneret and clog the extremely small extrusion holes of the NWF.

[0014] NWF meltblown fabrics are produced through special spinnerets to achieve higher technical characteristics than conventional TNT. In fact, meltblown fabrics are characterized by fibers with high filtering power against both liquid and gaseous substances.

[0015] A meltblown nonwoven production facility consists of a box that surrounds the meltblown fiber manufacturing device and all the parts necessary for the process to function optimally.

[0016] Known cusp melt blown plants include an extrusion head, a cusp distributor, and air blades.

[0017] Multi-row coaxial meltblown plants provide for stretching of polymer emerging from tubes arranged in rows in a coaxial fashion with air passing from the outside of the tubes and pushing the fibers downward.

[0018] In particular, a multi-row coaxial meltblown type plant comprises a component defining a coaxial bore adapted to accommodate at least a portion of the aforementioned tubes arranged in rows and passing coaxially inside the bore to allow diffusion of the polymerization fluid and simultaneously allow diffusion of air or gas from at least a portion of the bore.

[0019] These production facilities typically include a device called a spin pack, which contains several different components adapted to interact with each other. The spin pack typically consists of a spinneret and one or more diffusion devices, including components called air plates.

[0020] Even more particularly, currently known spinnerets for multi-row coaxial spunbond and / or meltblown plants further comprise a plate having a first hole adapted to accommodate a tube configured to distribute a polymerization fluid, and a second hole spaced from the first hole and adapted to allow the passage of air or gas, and a mask spaced from or integral with the plate, centered on the first hole, in fluid communication with the second hole, and having a plurality of third holes adapted to accommodate a portion of the tube while allowing the passage of air or gas.

[0021] As shown in FIG. 3, the first and second holes are generally arranged in a checkerboard pattern, with the second holes then being distributed in numbers equal to four around each feed hole.

[0022] The known techniques described have several important drawbacks.

[0023] In particular, the air passing through the second and third holes must be introduced under pressure and at a constant temperature to ensure that the filaments have the correct diameter, flow correctly, cool, and can be fed continuously without being destroyed.

[0024] The plant must therefore consume energy to ensure a constant flow rate and to heat the polymer and the air.

[0025] However, the current configuration of the spinneret is disadvantageous and makes processing polymeric filaments inefficient and inexpensive.

[0026] Furthermore, nonwoven layers produced with currently known spinnerets do not allow for the production of layers that perform particularly well when subjected to traction forces in different directions.

[0027] In fact, while nonwovens made in this way are very robust along the main direction of development of the plant, they are not so perpendicular to that direction.

[0028] The consequences of this weakness are very significant, for example, in the manufacture of diapers, which must be made with a very low weight, often equal to 5 g / m², and which include a sandwich structure with two outer spunbond layers and a central meltblown layer, which is mainly used to retain liquid.

[0029] The latter layers are usually made with a weight equal to 1-2 g / m2 and often break due to weakness along several directions, the tears thus compromising the liquid-tightness and main function of the diaper.

[0030] In this context, the technical problem underlying the present invention is to devise a spinneret for multi-row coaxial spunbond and / or meltblown type plants that is able to substantially avoid at least some of the aforementioned drawbacks.

[0031] In light of this technical problem, it is an important object of the invention to provide a spinneret for a spunbond and / or meltblown coaxial multi-row plant that can efficiently and economically deliver polymeric filaments.

[0032] It is a further object of the invention to realize a spinneret for multi-row coaxial spunbond and / or meltblown type plants that allows for the production of robust nonwoven films or layers in different directions, especially perpendicular to each other.

[0033] Another important object of the present invention is to provide a spinneret for a multi-row coaxial spunbond and / or meltblown type plant that allows for a robust diaper to be achieved by interlocking the different layers formed by the plant.

[0034] The technical problem and the specified object are achieved by a spinneret for a multi-row coaxial spunbond and / or meltblown type plant as claimed in the attached claim 1.

[0035] Preferred embodiments are highlighted in the dependent claims.

[0036] The features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0037] [Figure 1a] 1 shows a detailed front view of the third and second holes of a spinneret for a multi-row coaxial spunbond and / or meltblown plant according to the invention, where the second holes are hatched. [Figure 1b] A cross section corresponding to section II of the plant in FIG. 1a is shown. [Figure 2-1] FIG. 2a shows a detailed front view of the third and second holes of a spinneret for a multi-row coaxial spunbond and / or meltblown plant according to one embodiment, where the third hole includes acceleration conduits all having a circular profile. [Figure 2-2]Figure 2b is a detailed front view of the third and second holes of a spinneret for a multi-row coaxial spunbond and / or meltblown plant according to one embodiment, where the third holes all include acceleration channels with a cross-shaped profile. Figure 2c shows a detailed front view of the third and second holes of a spinneret for a multi-row coaxial spunbond and / or meltblown plant according to one embodiment, where the third holes all include acceleration channels with a cross-shaped profile. [Figure 2-3] FIG. 2d shows a detailed front view of the third and second holes of a spinneret for a multi-row coaxial spunbond and / or meltblown plant according to one embodiment, where the third hole includes an acceleration conduit having a partially circular profile and a partially cross-shaped profile. [Figure 3] 1 shows a chessboard configuration of the third and second holes of the spinneret for a prior art multi-row coaxial meltblown plant. [Figure 4] Figure 4a shows a simplified diagram of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where acceleration channels with opposite or complementary inclination angles are present in different rows. Figure 4b shows a simplified diagram of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the acceleration channels of a second row are perpendicular to the main plane and define a second inclination angle equal to 90°. [Figure 5] Figure 5a is a side view of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention in a side view, in which the rows of acceleration channels are made from the tubes of the multi-row coaxial meltblown type plant whose ends are in the same plane as the second end of the spinneret. Figure 5b shows a side view of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention in a side view, in which the rows of acceleration channels are made from the tubes of the multi-row coaxial meltblown type plant whose ends protrude from the second end of the spinneret. [Figure 6]1 shows an acceleration channel of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface is contoured like the inner surface. [Figure 7-1] Figure 7a shows a cross-sectional plan view of a first concave profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching, and Figure 7b shows a cross-sectional view of a second concave profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. [Figure 7-2] Figure 7c shows a cross-sectional view of a third concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. Figure 7d shows a cross-sectional view of a fourth convex-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention. Figure 7e shows a cross-sectional plan view of a fifth convex-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention. Figure 7f shows a cross-sectional plan view of a sixth concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. [Figure 7-3]Figure 7g shows a cross-sectional view of a seventh concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. Figure 7h shows a cross-sectional view of an eighth concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. Figure 7i shows a cross-sectional view of a ninth concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. Figure 7j shows a cross-sectional view of a tenth concave-shaped profile of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the convex portion is highlighted by hatching. [Figure 8]Figure 8a shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile in the shape of Figure 7a. Figure 8b shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile in the shape of Figure 7b. Figure 8c shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile in the shape of Figure 7c. Figure 8d shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile in the shape of Figure 7d. Figure 8e shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, wherein the outer surface has a cylindrical shape and a contour of the shape of Figure 7e. Figure 8f shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, wherein the outer surface has a cylindrical shape and a contour of the shape of Figure 7f. Figure 8g shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, wherein the outer surface has a cylindrical shape and a contour of the shape of Figure 7g. Figure 8h shows a perspective view of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, wherein the outer surface has a cylindrical shape and a contour of the shape of Figure 7h. Figure 8i shows a perspective view of an acceleration channel of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile of the shape of Figure 7i. Figure 8j shows a perspective view of an acceleration channel of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a cylindrical shape and a profile of the shape of Figure 7j. [Figure 9]Figure 9a shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a profile like the inner surface, and the conduits have the same profile on the same column and alternating profiles on the same row. Figure 9b shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a profile like the inner surface, and the conduits have the same profile. Figure 9c shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a profile like the inner surface, and the conduits abut and alternate with each other, with columns of conduits defining each circular profile. FIG. 9d shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface has a profile similar to the inner surface, and the conduits have the same profile on the same column and alternating concave and convex profiles on the same row. [Figure 10] Figure 10a shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, with a cylindrical outer surface and the conduits having the same concave contour. Figure 10b shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, with a cylindrical outer surface and the conduits having the same triangular convex contour. Figure 10c shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, with a cylindrical outer surface and the conduits having the same generally rectangular convex contour. Figure 10d shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, with a cylindrical outer surface and the conduits having the same generally star-shaped concave contour. [Figure 11]Figure 11a shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface is cylindrical and the conduits have the same concave profile, alternating in a checkerboard pattern with conduits having a circular profile. Figure 11b shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface is cylindrical and the conduits have two different concave profiles, alternating in a checkerboard pattern with conduits having different profiles. Figure 11c shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface is cylindrical and the conduits have two different, concave and convex, profiles, alternating in a checkerboard pattern with conduits having different profiles. FIG. 11d shows a cross-sectional view of the end of an acceleration conduit of a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention, where the outer surface is cylindrical and the conduit has two different profiles, one concave and one convex, with the conduits having different profiles alternating in a checkerboard manner. DETAILED DESCRIPTION OF THE INVENTION

[0038] As used herein, when measurements, values, shapes, and geometric references (such as perpendicular and parallel) are associated with words such as "approximately" or other similar terms, such as "almost" or "substantially," they are understood to exclude measurement errors or inaccuracies due to production and / or manufacturing tolerances, and in particular to have less than a slight deviation from the associated value, measurement, shape, or geometric reference. For example, when associated with a value, such terms preferably indicate a deviation of no more than 10% from the value itself.

[0039] Additionally, when terms such as "first," "second," "upper," "lower," "primary," "secondary," and the like are used, they do not necessarily specify a priority in order, relationship, or relative position, but may be used merely to clearly distinguish between different components thereof.

[0040] Unless otherwise specified, and as set forth in the discussion below, terms such as "processing," "calculating," "determining," "computing," or the like, are deemed to refer to the actions and / or processes of a computer or similar electronic computing device that manipulate and / or transform data represented as physical, e.g., electronic, quantities in a computer system and / or memory record with other data that is similarly represented as physical quantities within the computer system, record, or other information storage, transmission, or display device.

[0041] Unless otherwise stated, measurements and data reported herein are taken as provided in the International Standard Atmosphere ICAO (ISO 2533:1975).

[0042] Referring to the drawings, a spinneret for a multi-row coaxial spunbond and / or meltblown type plant according to the invention is generally referenced using the numeral 1.

[0043] The spinneret 1 is the part of the plant from which the polymer filaments produced from the polymer fluid directly exit. In a spunbond plant, the spinneret 1 is therefore the downstream part of the plant adapted to convey the polymer filaments onto a deposition surface to produce a nonwoven fabric.

[0044] Basically, the spinneret 1 can therefore be depicted as one or more perforated plates.

[0045] In a multi-row coaxial meltblown plant, the spinneret 1 can be defined by a spin pack. For example, the spinneret 1 can include a spinneret and an air plate.

[0046] The spinneret further includes a plurality of coaxial holes adapted to receive tubes arranged in rows and passing coaxially inside the holes to allow diffusion of the polymerization fluid and simultaneously allow air or gas from at least some of the holes to diffuse through the air plate.

[0047] In this case, the plant therefore provides for stretching of the polymer emerging from tubes arranged in rows by air passing coaxially from the outside of the tubes and pushing the fibres downwards.

[0048] In either case, preferably, the spinneret 1 develops mainly along a main axis 1a, which is an imaginary axis along which the spinneret 1 extends, for example the axis of gravity.

[0049] Furthermore, the spinneret 1 also extends along a main plane 1b, which can be provided, for example, by an intermediate plane that is preferably parallel to the support surface on which the polymeric filaments that make up the nonwoven fabric are deposited.

[0050] The main axis 1a is parallel to the main plane 1b and in some cases may be coplanar with it.

[0051] Furthermore, the spinneret 1 defines a vertical axis 1c.

[0052] The vertical axis 1c is preferably perpendicular to the main axis 1a. Therefore, the vertical axis 1c is also preferably perpendicular to the main plane 1b. Therefore, the vertical axis 1c is preferably oriented perpendicular to the support surface on which the polymerized filaments that make up the nonwoven fabric are deposited, and extends along the spinneret 1 from upstream to downstream.

[0053] The spinneret 1 includes a plurality of acceleration lines 2 .

[0054] If the spinneret 1 is part of a spunbond system, the acceleration conduit 2 can be made by a simple exit through-hole through which the polymer fluid is stretched and filaments are created.

[0055] If the spinneret 1 is part of a multi-row coaxial meltblown plant, the acceleration line 2 can be made of a tube through which the polymer fluid is stretched to create filaments, for example as shown in Figures 5a-5b.

[0056] In any case, each of the acceleration conduits 2 therefore extends along its own supply axis 2a.

[0057] The supply axis 2a is the axis along which the polymer fluid flows along the acceleration conduit 2. The supply axis 2a preferably traverses the main plane 1b, for example is perpendicular to the main plane 1b.

[0058] Thus, the acceleration conduits 2 are adapted to each feed a respective polymer filament along a feed axis 2a.

[0059] The device 1 therefore comprises a plate 7 and a mask 8 .

[0060] The plate 7 is essentially a geometric element that extends mainly along or parallel to the main plane 1b and whose out-of-plane dimension decreases with respect to the other two dimensions. In particular, the plate 7 extends mostly along the main plane 1b.

[0061] The plate 7 also includes a first hole 70 and a second hole 71 .

[0062] The first holes 70 are preferably configured to accommodate the acceleration conduits 2. In particular, each first hole 70 preferably accommodates a respective acceleration conduit 2. As already mentioned above, the acceleration conduits 2 are further configured to distribute the polymerization fluid.

[0063] The first hole 70 is therefore adapted to allow the passage of the polymerization fluid inside the acceleration conduit 2 .

[0064] The second holes 71 are instead spaced apart from the first holes 70. They are particularly adapted to allow the passage of air or gas.

[0065] Thus, essentially, the first hole 70 is adapted to accommodate a portion of the axis of the acceleration conduit 2 that is constrained relative to the support or internal air plate, while the second hole 71 is adapted to be placed in fluid communication with the ventilation conduit of the support through which air or gas flows.

[0066] Obviously, the plate 7 is essentially an intermediate air plate, while the mask 8 is an outer air plate.

[0067] In practice, the mask 8 is adjacent to the plate 7 along the vertical axis 1c, which means that the mask 8 is essentially placed downstream of the plate 7 relative to the feed direction of the polymerizing filaments.

[0068] Furthermore, the mask 8 preferably includes a plurality of third holes 80 .

[0069] The third holes 80 are preferably centered on the first holes 70. Moreover, they are adapted to accommodate the part of the acceleration conduit 2 emerging from the first holes 70 in the plate 7 while allowing the passage of air or gas. In practice, the third holes 80 are also fluidly connected to the second holes 71.

[0070] Advantageously, the second holes 71 are greater in number than 4. For example, the second holes 71 may be 5, 6 or even greater in number, for example up to 12.

[0071] Furthermore, the second holes 71 are advantageously distributed around at least some of the holes 70 , but preferably not all of the holes 70 .

[0072] Furthermore, the second hole 71 is centered along the circumference 7a, which is essentially an imaginary closed line.

[0073] Each circumference 7a extends parallel to the main plane 1b around a respective first hole 70 without touching any other first hole 70.

[0074] This means that the circumference 7 a along which the second holes 71 are distributed does not overlap the area occupied by the acceleration conduit 2 .

[0075] 1a and 2a-2d, the second holes 71 are distributed around each first hole 70 in numbers greater than four, at least around part of the first holes 70, preferably around all of the first holes 70. Thus, for each first hole 70, all second holes 71 are arranged around the first hole 70, advantageously distributed only along a circumference 7a extending around the first hole 70 parallel to said main plane 1b, preferably without touching any other first holes 70.

[0076] The second and third holes 71, 80 are preferably circular and parallel to the main plane 1b. The first hole 70 may be circular and / or have a profile like the acceleration conduit 2, which is parallel to the main plane 1b, as will be explained in more detail below.

[0077] Furthermore, and even more particularly, the first holes 70 may define a diameter comprised between 0.6 mm and 1 mm, and the second and third holes 71, 80 may define diameters comprised between 1.2 mm and 1.7 mm. Advantageously, however, the plate 7 and the mask 8 may be in a single piece.

[0078] This means that the terms plate 7 and mask 8 do not necessarily refer to different separate components of the spinneret 1, but in this case to parts of it.

[0079] In particular, the plate 7 and the mask 8 may be parts of the spinneret 1 that are substantially bounded by the main plane 1b.

[0080] The plate 7 is therefore adapted to be connected to a support, while the mask 8 faces outwards towards the rest of the multi-row coaxial spunbond or meltblown plant in which the spinneret 1 is installed.

[0081] The plate 7 also faces normally upwards, while the mask 8 pivots downwards.

[0082] The terms high and low are interpreted relative to the ground. In practice, multi-row coaxial spunbond or meltblown plants typically distribute the polymerizing fluid towards the support surface of, for example, a conveyor moving parallel to the ground.

[0083] The plate 7 therefore defines at least a first end 10 of the spinneret 1 .

[0084] First end 10 is adapted to interface with a polymeric fluid distributor of a multi-row coaxial spunbond and / or meltblown type plant. First end 10, in turn, is the exposed portion of spinneret 1 upstream of spinneret 1 through which polymeric fluid is delivered.

[0085] For example, the first end 10 can be made by a face of the plate 7 parallel to the main plane 1b, adapted to be restrained against a distributor of the plant.

[0086] The mask 8 also defines a second end 11 of the spinneret 1 .

[0087] The second end 11 is located on the opposite side of the spinneret 1 from the first end 10 relative to the main plane 1b. Moreover, the second end 11 is the part from which the polymer fluid is discharged from the spinneret 1 in the form of polymer filaments.

[0088] The second end 11 is therefore a part of the spinneret 1, in particular the mask 8, that is exposed downstream of the spinneret 1 and adapted to convey the polymerized filaments towards a support surface.

[0089] For example, the second end 11 can be made from a surface of the mask 8 that is parallel to the main plane 1b facing the support surface.

[0090] In either case, the acceleration conduits 2 extend from the plate 7 towards the mask 8 so that they extend at least from a first end 10 to a second end 11 .

[0091] It is important to note, particularly in the case of a multi-row coaxial meltblown plant, that the end of the acceleration line 2 may be in the same plane as the second end 11 or it may also protrude from the second end 11 to the outside of the spinneret 1.

[0092] In addition to what has been described so far, the acceleration conduits 2 are distributed along a distribution axis 2b, which is preferably transverse to the main axis 1a and the vertical axis 1c. The acceleration conduits 2 are then distributed along the distribution axis 2b so as to realize a first row 2' along the distribution axis 2b.

[0093] Furthermore, the acceleration conduits 2 are also distributed along and parallel to the main axis 1a so as to realize at least a second row 2''.

[0094] Thus, the second row 2'' is preferably offset along the major axis 1a relative to the first row 2'.

[0095] Moreover, advantageously, at least one of the supply axes 2a of the acceleration conduits 2 of the first row 2' defines a first tilt angle α'.

[0096] A first tilt angle α' is defined relative to the main plane 1b. Moreover, advantageously, the first tilt angle α' is other than 90°. For example, the first tilt angle α' may be comprised between 60° and 90°.

[0097] Moreover, at least one of the supply axes 2a of the acceleration conduits 2 of said second row 2' defines a second tilt angle α''.

[0098] A second tilt angle α'' is also defined relative to the main plane 1b. Moreover, advantageously, the second tilt angle α'' is different from the first tilt angle α'.

[0099] This means that at least one pair of acceleration conduits 2 of different rows 2', 2'' is inclined differently to supply polymer filaments so that the polymer filaments can, for example, converge with other polymer filaments.

[0100] In particular, as shown in Figures 4a-4b, preferably, the supply axes 2a of all acceleration conduits 2 of the first row 2' and / or the second row 2'' define the same first inclination angle α' and / or the same second inclination angle α'', respectively.

[0101] Even more particularly, one or more of the second tilt angles α″, for example all second tilt angles α″ as shown in FIG. 4b, may be equal to 90°.

[0102] Or again, the second tilt angle α'' may be opposite or additional to the first tilt angle α', as shown, for example, in FIG. 4a.

[0103] Thus, as already mentioned, the acceleration channel 2 is an element of substantially elongated shape containing a cavity which can be penetrated by the liquid polymer and in particular enable it to be extruded from the spinneret 1 .

[0104] The acceleration conduit 2 therefore comprises at least one inner surface 3 .

[0105] The inner face 3 is substantially closed and, moreover, it unfolds around the feed axis 2a since it actually faces towards it.

[0106] The inner surface 2 therefore surrounds a cavity.

[0107] Moreover, the acceleration conduit 2 defines a plurality of contours 4. The contours 4 are identical to one another. Moreover, they are arranged successively along the feed axis 2a.

[0108] A contour 4 is therefore substantially formed along the feed axis 2a by the inner surface 3 and determines the overall shape of the cavity.

[0109] In particular, the contour 4 is preferably determined on the cross section 2c.

[0110] The cross section 2c is preferably perpendicular to the supply axis 2a and is therefore essentially an imaginary plane that cuts the acceleration conduit 2 perpendicularly to the supply axis 2a and thereby defines on itself the contour 4 formed by the inner surface 3.

[0111] The contour 4 also defines a first extended area, which is a portion of the two-dimensional space contained within the contour 4.

[0112] Therefore, the contour 4 can preferably be depicted in a circle, which is also determined on the cross section 2c. Naturally, a circle is a trivially imaginary geometric element inside which the contour 4 can be geometrically depicted.

[0113] Furthermore, the circle itself defines a second area of ​​extension on the cross section 2c, which is therefore determined by the two-dimensional space contained within the circle, which, as is known, can be obtained by the formula A=π*r2.

[0114] Advantageously, the contour 4 does not have a shape corresponding to a circle.

[0115] In practice, advantageously, the first extending area is less than 90% of the second extending area, and even more particularly, preferably, the first extending area is less than 60% of the second extending area.

[0116] The contour 4 can therefore be made according to different embodiments.

[0117] For example, the contour 4 may be a convex form. As is known, a convex form is one in which any line segment joining any two of its points is completely contained within the form itself.

[0118] Thus, when the contour 4 is convex, it preferably defines a first dimension 4a and a second dimension 4b.

[0119] The first dimension 4a is essentially the maximum dimension that the contour 4 defines in one direction, and the second dimension 4b is the maximum dimension in a direction perpendicular to the first dimension 4a.

[0120] Preferably, the second dimension 4b is less than 90% of the first dimension 4a. Even more particularly, the second dimension 4b may be less than 60% of the first dimension 4a.

[0121] Furthermore, the dimensions may refer to a geometrically well-defined contour 4. For example, the convex contour 4 may have the shape of an almost equilateral triangle, as shown in Figure 7e, or a quasi-rectangle, possibly with additionally slightly rounded sides, as shown in Figure 7d.

[0122] Of course, in the case of a triangle, the first dimension 4a may be given by the height, while the second dimension 4b may be given by the side intersected by the height. In the case of a rectangle, the dimensions 4a, 4b may correspond to the respective sides.

[0123] In other embodiments, the contour 4 may instead be concave. In conjunction with convexity, concavity of a feature is exhibited when there is at least one line segment connecting a pair of points of the feature that does not belong entirely to the feature itself.

[0124] Thus, if the contour 4 is concave, it preferably includes at least one convex portion 40. A convex portion 40 is identifiable within the contour 4 as being at least partially delimited, and is a part of the concave contour 4 that has the characteristic of being convex.

[0125] Thus, convex portion 40, like convex contour 4, can also define a third dimension 40a and a fourth dimension 40b.

[0126] The third dimension 40a is essentially the largest dimension in one direction that the convex portion 40 extends, and the fourth dimension 40b is also the largest dimension in a direction perpendicular to the third dimension 40a.

[0127] Preferably, the fourth dimension 40b is less than 90% of the third dimension 40a. Even more particularly, the fourth dimension 40b may be less than 60% of the third dimension 40a.

[0128] As mentioned above, the dimensions may refer to a geometrically well-defined convex portion 40. For example, the convex portion 40 of the contour 4 may have a generally triangular shape, as shown in Figure 7h, or a generally rectangular shape, as shown in Figures 7g and 7j, possibly a shape with chamfered sides, as shown in Figure 7a, or even a trapezoidal shape, as shown in Figures 7b-7c.

[0129] Of course, in the case of a triangle, the first dimension 4a may be given by the height, while the second dimension 4b may be given by the base side on which the height lies. In the case of a rectangle, the dimensions 4a, 4b may correspond to the respective sides.

[0130] More generally, the concave contour 4 may be formed by two or more mutually intersecting convex portions 40. The concave contour 4 may thus define a cross / star shape with three to five points (for example, three as in Figures 7a and 7c, or four as in Figures 7f and 7i, or even five as in Figures 7b and 7j).

[0131] In addition to what has been described so far, particularly if the acceleration conduit 2 is a tube, it may also include an outer surface 5 .

[0132] The outer surface 5 is also closed. Moreover, the outer surface 5 extends around the inner surface 3. And the outer surface 5 wraps around the inner surface 3.

[0133] Preferably, the outer surface 5 of the acceleration conduit 2, facing the outside and therefore not in contact with the cavity, is also connected to the inner surface 3 via a wall 6.

[0134] The wall 6 is therefore bounded by the surfaces 3, 5, which therefore define the two faces of the wall 6 relative to the same wall 6.

[0135] The outer surface 6 may therefore be cylindrical, as shown in Figures 8a-8j, 10a-10d, and 11a-11d, or the outer surface 5 may alternatively have a contour like the inner surface 3. In this way, the surfaces 3, 5 determine a constant thickness for the wall 6, as shown, for example, in Figures 5 and 9a-9d.

[0136] Of course, the acceleration line 2 can also be used together with other acceleration lines 2 to form a group of acceleration lines 2, for example a pack, for use within a plant.

[0137] Thus, in various embodiments, the spinneret 1 may include multiple acceleration conduits 2 all defining the same contour 4, as in Figures 9a-9d.

[0138] Or, a chain 1 may include several such acceleration conduits 2 each defining a different contour 4, as in Figures 9a-9d and 11b-11d.

[0139] Alternatively, the spinneret 1 may comprise a number of acceleration channels 2 each defining a circular profile, ie having a conventional profile according to known technology, as in Figures 9c and 9a.

[0140] For example, the spinneret 1 may also include multiple acceleration channels 2, each defining a circular outline, but with different diameters.

[0141] Of course, the invention also comprises a multi-row coaxial spunbond and / or meltblown plant having a spinneret 1 as just described according to different possible embodiments.

[0142] The operation of the spinneret 1 for a multi-row coaxial spunbond and / or meltblown type plant described above in structural terms is substantially similar to that of any prior art spinneret in the sense that it allows the polymer fluid to be transported along the feed axis 2a of each acceleration conduit 2.

[0143] However, the spinneret 1 for a multi-row coaxial spunbond and / or meltblown type plant according to the present invention achieves important advantages.

[0144] In fact, the spinneret 1 for multi-row coaxial spunbond and / or meltblown plants is very efficient and economical because the secondary hole distribution increases the effectiveness of the exhaust air, allowing the air temperature to be increased with the same heat input, thereby making the polymerized filaments more extendible, thus reducing the cost required to heat the air.

[0145] The latter has a smaller diameter, which reduces the chance of filament breakage while increasing dispensing control.

[0146] Furthermore, the spinneret 1 for multi-row coaxial spunbond and / or meltblown type plants allows for the production of strong nonwoven films or layers in different directions, especially perpendicular to each other.

[0147] The fact that the filaments are discharged in different directions at different inclinations makes it possible to achieve robustness of the fabric not only parallel to the main axis 1a but also transverse to it, i.e. parallel to the distribution axis 2b.

[0148] Thus, the spinneret 1 for a multi-row coaxial spunbond and / or meltblown type plant also makes it possible to create a more resistant, sturdy and robust diaper, which is achieved by connecting the different layers formed by the plant, especially the weaker layers, which are less likely to break.

[0149] The invention can be modified to produce different versions that fall within the scope of the inventive concept defined by the claims.

[0150] In this context, all details may be replaced by equivalent elements and any materials, shapes and dimensions may be used. (Other possible items) (Item 1) A spinneret (1) for a multi-row coaxial spunbond and / or meltblown type plant, extending along a major axis (1 a) and a major plane (1 b) and defining a vertical axis (1 c) perpendicular to said major axis (1 a) and said major plane (1 b), a plurality of acceleration conduits (2), each extending along its own feed axis (2a) transverse to said main plane (1b), each adapted to feed a respective polymerized filament along said feed axis (2a); - a plate (7), said plate (7) comprising: a first hole (70) adapted to accommodate said acceleration conduit (2), and - having a second hole (71) spaced apart from said first hole (70) and adapted to allow said passage of air or gas; a mask (8) adjacent to the plate (7) along the vertical axis (1 a), centered on the first hole (70), in fluid communication with the second hole (71), and having a plurality of third holes (80) adapted to accommodate a portion of the acceleration conduit (2) while allowing the passage of the air or gas; - said second holes (71) are distributed around at least a portion of said first holes (70) in a number greater than four around each said first hole (70); - a spinneret (1) in which, for each said first hole (70), all said second holes (71) are distributed around said first hole (70) only along a circumference (7a) extending parallel to said main plane (1b) around the respective said first hole (70) without touching any other said first hole (70). (Item 2) 2. The spinneret (1) according to item 1, wherein the plate (7) and the mask (8) are in one piece. (Item 3) 3. The spinneret (1) according to item 1 or 2, wherein each of the second holes and the third holes (71, 80) is circular and parallel to the main plane (1 b), and one or more of the first holes (70) is circular and / or has a profile like each of the acceleration channels (2) parallel to the main plane (1 b). (Item 4) 4. The spinneret (1) according to item 3, wherein the first holes (70) define a diameter between 0.6 mm and 1 mm, and the second holes and the third holes (71, 80) define a diameter between 1.2 mm and 1.7 mm. (Item 5) The plate (7) defines a first end (10) of the spinneret (1) adapted to interface with a polymerizing fluid distributor of a multi-row coaxial spunbond and / or meltblown plant, the mask (8) defines a second end (11) of the spinneret (1) located on a side of the spinneret (1) opposite the first end (10) relative to the main plane (1b) where the polymerizing fluid exits the spinneret (1) in the form of the polymerizing filaments; the acceleration conduit (2) defines a distribution axis transverse to the main axis (1a) and the vertical axis (1c) to create first rows (2'). 5. The spinneret (1) according to item 4, wherein the acceleration channels (2) are distributed not only along the main axis (1 a) but also parallel to the main axis (1 a), and at least one second row (2'') is offset from the first row (2') along the main axis (1 a); at least one of the feed axes (2 a) of the acceleration channels (2) of the first row (2') defines a first inclination angle (α') other than 90° with respect to the main plane (1 b), and at least one of the feed axes (2 a) of the acceleration channels (2) of the second row (2'') defines a second inclination angle (α'') with respect to the main plane (1 b) that is different from the first inclination angle (α'). (Item 6) 6. The spinneret (1) according to item 5, wherein the feed axes (2a) of all the acceleration conduits (2) of the first row (2') and / or the second row (2'') respectively define the same first inclination angle (α') and / or the same second inclination angle (α''). (Item 7) 7. The spinneret (1) according to item 5 or 6, wherein one or more of the second inclination angles (α″) is equal to 90°. (Item 8) 8. The spinneret (1) according to any one of items 5 to 7, wherein the second tilt angle (α'') is opposite to or in addition to the first tilt angle (α'). (Item 9) 9. The spinneret (1) according to any one of items 5 to 8, wherein the first tilt angle (α') is between 60° and 90°. (Item 10) One or more of the acceleration conduits (2) have at least one closed inner surface (3) extending around the supply axis (2a) and defining a plurality of identical contours (4) arranged successively along the supply axis (2a); the contours (4) are determined on a cross section (2c) perpendicular to the supply axis (2a); the contours (4) define a first extension area on the cross section (2c); the contours (4) are delineable within a circle determined on the cross section (2c); the circle defines a second extension area on the cross section (2c); - The spinneret (1) according to any one of items 1 to 9, wherein the first extension area is less than 90% of the second extension area. (Item 11) Item 11. The spinneret (1) according to item 10, wherein the first extension area is less than 60% of the second extension area. (Item 12) 12. The spinneret (1) according to any one of the preceding claims, wherein the contour (4) is convex and defines at least a first maximum dimension (4a) and a second maximum dimension (4b) that is perpendicular to the first maximum dimension (4a) and is less than 90% of the first maximum dimension (4a). (Item 13) Item 12. The spinneret (1) according to item 10 or 11, wherein the contour (4) is concave and includes at least one convex portion (40) that is discernible within the contour (4) as being bounded by at least a portion of the contour (4) and defines at least a third maximum dimension (40a) and a fourth maximum dimension (40b) that is perpendicular to the third maximum dimension (40a) and is less than 90% of the third maximum dimension (40a). (Item 14) 14. The spinneret (1) according to any one of the preceding claims, wherein the contour (4) is formed by two or more of the convex portions (40) intersecting each other. (Item 15) 15. The spinneret (1) according to the previous item 14, comprising a plurality of acceleration conduits (2) which all define the same contour (4) or contours (4) which differ from one another and / or are one or more of the circular type.

Claims

1. 1. A spinneret for a multi-row coaxial spunbond and / or meltblown type plant, extending along a major axis and a major plane and defining a vertical axis perpendicular to said major axis and said major plane, comprising: a plurality of acceleration conduits, each extending along its own feed axis transverse to said main plane and each adapted to feed a respective polymerized filament along said feed axis; - a plate, said plate comprising: a first bore adapted to accommodate said acceleration conduit, and - having a second hole spaced apart from the first hole and adapted to allow the passage of air or gas; a mask adjacent to the plate along the vertical axis, centered on the first hole, and having a plurality of third holes in fluid communication with the second holes, adapted to accommodate a portion of the acceleration conduit while allowing the passage of the air or gas; - said second holes are distributed around at least a portion of said first holes in a number greater than four around each said first hole; - a spinneret in which, for each said first hole, all said second holes are distributed around said first hole only along a circumference extending parallel to said main plane around the respective said first hole without touching any other said first hole.

2. 10. The spinneret of claim 1, wherein the plate and the mask are one piece.

3. 2. The spinneret of claim 1, wherein each of the second and third holes is circular and parallel to the major plane, and one or more of the first holes is circular and / or has a profile like the respective acceleration channel that is parallel to the major plane.

4. 4. The spinneret of claim 3, wherein the first hole defines a diameter between 0.6 mm and 1 mm, and the second hole and the third hole define diameters between 1.2 mm and 1.7 mm.

5. The plate defines a first end of the spinneret adapted to interface with a polymerization fluid distributor of a multi-row coaxial spunbond and / or meltblown plant, the mask defines a second end of the spinneret disposed on a side of the spinneret opposite the first end relative to the major plane where polymerization fluid exits the spinneret in the form of the polymerized filaments; and the acceleration conduit aligns the major axis and the vertical axis to create a first rank.

5. The spinneret of claim 4, wherein the feed axes of the acceleration conduits of the first row define a first inclination angle other than 90° with respect to the major plane, and the feed axes of the acceleration conduits of the second row define a second inclination angle with respect to the major plane that is different from the first inclination angle.

6. 6. The spinneret of claim 5, wherein the feed axes of all the acceleration conduits of the first row and / or the second row define the same first inclination angle and / or the same second inclination angle, respectively.

7. 6. The spinneret of claim 5, wherein one or more of the second tilt angles is equal to 90 degrees.

8. 6. The spinneret of claim 5, wherein the second tilt angle is opposite or additive to the first tilt angle.

9. 6. The spinneret of claim 5, wherein the first tilt angle is comprised between 60° and 90°.

10. One or more of the acceleration conduits extend around the supply axis and have at least one closed inner surface defining a plurality of identical contours arranged successively along the supply axis; the contours are determined on a cross section perpendicular to the supply axis; the contours define a first extension area on the cross section; the contours are describable within a circle determined on the cross section; and the circle defines a second extension area on the cross section; A spinneret according to any one of claims 1 to 9, wherein the first extension area is less than 90% of the second extension area.

11. 11. The spinneret of claim 10, wherein the first extension area is less than 60% of the second extension area.

12. 11. The spinneret of claim 10, wherein the profile is convex and defines at least a first maximum dimension and a second maximum dimension that is perpendicular to the first maximum dimension and that is less than 90% of the first maximum dimension.

13. 11. The spinneret of claim 10, wherein the contour is concave and includes at least one convex portion discernable within the contour as bounded by at least a portion of the contour and defining at least a third maximum dimension and a fourth maximum dimension perpendicular to the third maximum dimension and less than 90% of the third maximum dimension.

14. 14. The spinneret of claim 13, wherein the profile is formed by two or more of the convex portions intersecting each other.

15. 15. The spinneret of claim 14, comprising a plurality of said acceleration conduits, all defining the same contour or said different contours, and / or being one or more of the circular type.

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