Multi-row coaxial melt-blown type plant

Abstract

A multi-row coaxial melt-blown type plant (1) is provided comprising a support (2) including one or more first conduits (20) configured to convey polymeric fluid parallel to a dispensing direction (2a) and at least one second conduit (21) configured to convey air or gas, a cassette (3) removably constrained to the support (2) and including a plurality of acceleration conduits (30) extending parallel to the dispensing direction (2a) comprising tubes (10) in fluid passage connection with one or more first conduits (20) and configured to distribute the polymeric fluid, first holes (31) extending parallel to the dispensing direction (2a), centered and spaced with respect to the acceleration conduits (30) along the dispensing direction (2a) and configured to house each part of a respective tube (10), second holes (32) extending parallel to the dispensing direction (2a) and adapted to allow the passage of air or gas, and a slit (33) extending transversely to the dispensing direction (2a) between the acceleration conduits (30) and the first holes (31) in fluid passage connection with the second holes (32), wherein the support (2) comprises a housing (22) configured to contain the cassette (3) and the slit (33) extends in the cassette (3) from side to side so as to be in fluid passage connection with the second conduit (21) and configured to convey air or gas from the second conduit (21) to the second holes (32).

Description

[0001] The object of the present invention is a multi-row coaxial melt-blown type plant of the type specified in the preamble to the first claim.

[0002] In other words, the present invention has as its object a plant adapted to allow the realization of filaments of extruded polymers intended to directly or indirectly make fabric of the nonwoven fabric type, also known as NWF.

[0003] As is known, nonwoven fabric, or NWF, is an industrial product similar to a fabric but obtained by processes other than weaving and knitting. Therefore, within an NWF, the fibers have a random pattern, with no identifiable ordered structure while in a fabric the fibers have two prevailing and orthogonal directions between them, usually called weft and warp.

[0004] Currently, a plurality of products containing NWF are manufactured depending on the manufacturing technique used, mainly connected to the use that is made of the product itself.

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

[0006] From a technical point of view, nonwoven fabrics, can be basically divided into spunlace, spunbond and melt-blown.

[0007] In the field of melt-blown technology, in particular, multi-row coaxial melt-blown type plants are known. An example of such plants is shown in Figs. 5-7.

[0008] In general, such plants provide for stretching the polymer that comes out of tubes, arranged in rows, and intercepts an air flow that, in a coaxial manner, passes from the outside of the tube and pushes the fiber downwards.

[0009] In particular, multi-row coaxial melt-blown type plants comprise components defining coaxial holes, arranged in rows and adapted to house at least part of the aforementioned tubes transiting coaxially inside the holes in such a way as to allow the diffusion of polymeric fluid and, at the same time, the diffusion of air or gas from at least part of the holes.

[0010] Usually, these plants include devices, called spin packs, providing a plurality of different components adapted to interact with each other. Usually, a spin pack consists of a spinneret and a diffusion device including one or more components called air plates.

[0011] Furthermore, the spinneret may in turn be connected to a taper and / or a breaker-plate.

[0012] If present, the breaker-plate is also connected to an extrusion head suitable for conveying at least polymeric fluid and possibly also air or gas under pressure to the spin pack. The breaker-plate and the taper basically have the same characteristics as the breaker-plate and taper used in spunbond and melt-blown technologies. Multi-row coaxial melt-blown plants including spin packs, however, do not comprise a diffusion device including a support adapted to support an air blade, do not comprise a cusp or do not have a simple spinneret adapted to exclusively allow the escape of polymer.

[0013] In multi-row coaxial melt-blown type plants, the spinneret is basically a support that allows the support of tubes adapted to eject polymer filaments. The diffusion device is, therefore, coupled to the spinneret and comprises an intermediate plate, or air plate, adapted to allow the passage of the aforementioned tubes and also the escape of air or other gas under pressure, and an outer jig, or outer air plate, usually of divergent shape, from which the polymeric filament emerges, pushed downwards from the air, before reaching the conveyor belts present in any plant for the manufacture of nonwoven fabric.

[0014] Multi-row coaxial melt-blown devices comprise some significant drawbacks.

[0015] In particular, to make a melt-blown nonwoven fabric, it is necessary that the tubes pass through the support, the plate and the outer jig without losing coaxiality with respect to the holes made, in particular, on the plate and jig in order to guarantee a correct operation of the plant. In fact, it is possible that the ends of the tubes coming out of the outer jig through the holes, configured with a diameter greater than the tubes in such a way as to allow the outflow of air or gas, may also undergo deformations. This possibility is mainly due to the need to maintain at least one slot between the plate and the outer jig for the distribution of gas or air.

[0016] Furthermore, the plants as described above have a plurality of overlapping plates and are not very compact and are difficult to disassemble.

[0017] The use of many plates during installation, on the other hand, involves considerable problems once the plants have undergone a plurality of processes. In fact, it is necessary that the plates and jigs fit all the tubes perfectly. In addition, it is necessary that the outer plate and jig are perfectly aligned with each other in such a way as to avoid unwanted overlaps that could lead to breakage of tubes or the impossibility of mounting the intermediate and outer air plates to the inner air plate. These problems are extremely amplified by the high processing temperatures and expansions that can occur in the various components of multi-row coaxial melt-blown type plants.

[0018] In addition, all the aforementioned problems are greatly amplified when the spin pack is particularly extensive since assembling or disassembling the air plate from the tubes can entail the need to enormously increase the force necessary to overcome the mutual frictions between air plates and tubes.

[0019] In addition, the multi-row coaxial melt-blown type plants of the prior art define a fixed configuration through which it is substantially only possible to deposit one or more rows of nonwoven fabric starting from the same spinneret.

[0020] Therefore, if a second row of polymeric filament is to be deposited on the conveyor roller, it is necessary to have a second device comprising at least one extrusion head, breaker plate and spin pack.

[0021] Of course, this need has, in economic terms, an enormous impact substantially caused by the sum of the costs of the plants, in addition to the sum of the management and maintenance costs.

[0022] In this situation, the technical task underlying the present invention is to devise a multi-row coaxial melt-blown type plant that can substantially obviate at least part of the above-mentioned drawbacks.

[0023] Within this technical task, it is an important object of the invention to obtain a multi-row coaxial melt-blown type plant that facilitates the assembly and disassembly of one or more components of the plant.

[0024] Another important object of the invention is therefore to realise a plant the maintenance of which is simple, fast, effective and economical.

[0025] In addition, a further task of the invention is to realise a plant that is extremely versatile and that makes it possible to modify in a simple way the conformation, understood for example as density or number, of the tubes from which the polymeric filaments emerge.

[0026] Furthermore, it is an important object of the invention to obtain a multi-row coaxial melt-blown type plant that allows more than a single row of polymeric filament to be made.

[0027] Therefore, another important object of the invention is to realize a multi-row coaxial melt-blown type plant that makes it possible to reduce the number of components necessary to realize the aforementioned advantages.

[0028] In conclusion, a further task of the invention is to realize a multi-row coaxial melt-blown type plant that makes it possible to use at least in part the components of traditional plants in such a way as to reduce the conversion costs of the plants. The technical task and the specified objects are achieved by a multi-row coaxial melt-blown type plant as claimed in the attached Claim 1.

[0029] Preferred technical solutions are highlighted in the dependent claims.

[0030] The features and advantages of the invention are clarified below by the detailed description of preferred embodiments of the invention, with reference to the attached drawings, in which: Fig. 1 shows a cross-sectional view along the main plane of a multi-row coaxial melt-blown type plant according to the invention in a first embodiment wherein the spinneret comprises two groups and wherein the distributor comprises a plurality of main accesses; Fig. 2 illustrates a cross-sectional exploded view along the main plane of a multi-row coaxial melt-blown type plant according to the invention in a second embodiment wherein the distributor comprises a single main access; Fig. 3 is a cross-sectional view along the main plane of a multi-row coaxial melt-blown type plant according to the invention in a third embodiment wherein the spinneret comprises a group and a cusp; Fig. 4 represents an exploded view of the plant of Fig. 3; Fig. 5a shows a view at the main plane of the ends of the branches of the transfer device of a multi-row coaxial melt-blown type plant according to the invention wherein only a main and a secondary end of the same group are aligned; Fig. 5b shows a view at the main plane of the ends of the branches of the transfer device of a multi-row coaxial melt-blown type plant according to the invention wherein all the ends of the same group are aligned; Fig. 6 illustrates a cross-sectional view of a multi-row coaxial melt-blown type plant of the prior art wherein the holes of the intermediate air plate through which the air flows are highlighted; Fig. 7 is a further cross-sectional view of a multi-row coaxial melt-blown type plant of the prior art wherein the housing holes of the tubes that distribute polymeric fluid are highlighted; and Fig. 8 shows an exploded and perspective view of a multi-row coaxial melt-blown type plant of the prior art wherein the following are shown, from bottom to top: an outer air plate, an intermediate air plate, an inner air plate, a taper, a breaker plate and a second taper intended to be constrained in contact with an extrusion head.

[0031] In this document, when measurements, values, shapes, and geometric references (such as perpendicularity and parallelism) are associated with words like "approximately" or other similar terms, such as "almost" or "substantially", they are to be understood as excluding measurement errors or inaccuracies due to production and / or manufacturing errors and, above all, as having less than a slight deviation from the associated value, measurement, shape, or geometric reference. For example, such terms, when associated with a value, preferably indicate a deviation of no more than 10% of that value.

[0032] Moreover, when used, terms such as "first", "second", "upper", "lower", "main" and "secondary" do not necessarily identify an order, a priority of relationship or a relative position, but can simply be used to clearly distinguish between their different components.

[0033] Unless otherwise specified, as reflected in the following discussions, terms such as "processing", "computing", "determination", "calculation", or the like are considered to refer to the action and / or processes of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical, such as electronic quantities of records of a computer system and / or memories, in other data similarly represented as physical quantities within computer plants, records, or other information storage, transmission, or display devices.

[0034] Unless otherwise stated, the measurements and data reported in this text shall be considered as provided in International Standard Atmosphere ICAO (ISO 2533:1975).

[0035] With reference to the figures, the multi-row coaxial melt-blown type plant according to the invention is globally referred to with the numeral 1.

[0036] The plant 1, as per the title, includes some features of common melt-blown plants and other special measures.

[0037] In particular, the plant 1 preferably comprises at least one distributor 2 and a dispenser 3.

[0038] The following description of all the components that may be present in a plant 1 is made considering the same along a cross section of the plant in a main plane 1a, or a secondary plane 1a' parallel to the main plane 1a, as depicted for example in Figs. 1-4. Of course, such a plant 1 and the components that compose it also extend along a longitudinal direction 1b perpendicular to the main plane 1a and secondary plane 1a' or to the cross sections mentioned.

[0039] Thus, substantially, the main plane 1a and secondary section plane 1a' are mutually offset along the longitudinal direction 1b.

[0040] The distributor 2 is basically a device adapted to allow the distribution of polymeric fluid and air inside respective conduits for the realization of a diffusion path.

[0041] The distributor 2 is therefore configured to be operatively connected to a cassette 10.

[0042] The cassette 10 is substantially a conventional element of a melt-blown plant. In particular, the cassette 10 is the portion through which the polymeric fluid and the gas are conveyed to the distributor 2.

[0043] Thus, the cassette 10 comprises at least one main conduit 10a adapted to convey polymeric fluid and a plurality, for example a pair, of secondary conduits 10b adapted to convey gas.

[0044] The distributor 2 therefore comprises at least one main access 20.

[0045] The main access 20 is adapted to be placed in fluid passage connection with the main conduit 10a. Thus, the main access 20 is the portion through which the polymeric fluid accesses the distributor 2.

[0046] The distributor 2 further comprises at least one secondary access 21. Preferably, the distributor 2 comprises a plurality of secondary accesses 21.

[0047] The secondary accesses 21 are adapted to be placed in fluid passage connection each with a respective secondary conduit 10b. Therefore, the secondary accesses 21 define the portions through which the gas accesses the distributor 2.

[0048] The dispenser 3 is preferably in fluid passage connection with the distributor 2. In particular, the dispenser 3 receives both the polymeric fluid and the gas from the distributor 2.

[0049] Then, the dispenser 3 is configured to dispense polymeric filaments from the polymeric fluid.

[0050] Therefore, in this regard, the dispenser 3 comprises at least one spinneret 4.

[0051] The spinneret 4 is adapted to form polymeric filaments. Furthermore, the spinneret 4 is preferably removably constrained to the distributor 2.

[0052] Hence, the spinneret 4 includes at least one group 4'.

[0053] The group 4' is substantially a set of elements. In detail, the group 4' comprises a plurality of acceleration conduits 40.

[0054] The acceleration conduits 40 preferably develop parallel to a dispensing direction 4a.

[0055] The dispensing direction 4a is preferably defined parallel and in detail along the main plane 1a.

[0056] Further, the acceleration conduits 40 are substantially configured to receive the first polymeric fluid from the at least one main access 20. Thus, the acceleration conduits 40 are preferably arranged in fluid passage connection with the main access 20. Further, the acceleration conduits 40 are preferably configured to accelerate the first polymeric fluid.

[0057] In this regard, in multi-row coaxial melt-blown type plants, the acceleration conduits include, or may consist of, tubes 11. These tubes 11 can, therefore, be releasably bound to the spinneret 4.

[0058] The tubes 11 are widely known to the current state of the art and are substantially conduits including at least one inner converging section (according to the filament advancement direction) adapted to allow the acceleration of the first polymeric fluid in transit inside them.

[0059] In addition, the tubes 11 have a substantially tubular cylindrical and / or, at least in part, conical shape and define diameters usually between 0.6 and 1 mm.

[0060] The tubes 11 are also intended to extend through the dispenser 3, as shown in Figs. 1 and 3.

[0061] If the tubes 11 are not in one piece with the spinneret 4, usually, the support includes the housings.

[0062] The housings may be substantially cavities, including at least one shoulder or step, within which the tube 11 may be at least partially housed.

[0063] The tube 11, in fact, in turn, preferably includes a base and a stem.

[0064] The base is preferably configured to be inserted into one of the housings.

[0065] The stem preferably extends parallel to the dispensing direction 4a, i.e. in a vertical direction along the cross-section. Thus, the first polymeric fluid coming from the main access 20 substantially enters the base of the tubes 11 and is accelerated along the stems.

[0066] Hence, the tubes 11 are substantially in fluid passage connection with at least one main access 20 and are configured to distribute said polymeric fluid,

[0067] The acceleration conduits 40 may then be distributed along one or more rows extending parallel to the longitudinal direction. In particular, they are usually distributed in a regular manner such as to create rows ordered both along the longitudinal direction and along each cross section of the plant 1.

[0068] Sometimes, the acceleration conduits 40 of adjacent rows are mutually offset along the longitudinal direction 1b in such a way as to realize a substantially checkerboard configuration.

[0069] The group 4' also includes first holes 41 and second holes 42.

[0070] The first holes 41 preferably extend parallel to the dispensing direction 4a. Furthermore, they are preferably centered with respect to the acceleration conduits 40 along the dispensing direction 4a. Then, the first holes 41 are preferably configured to house each part of a respective tube 11. The tubes 11, as already mentioned, are in turn configured to distribute polymeric fluid.

[0071] Therefore, the first holes 41 are adapted to allow the passage of polymeric fluid through the tubes 11.

[0072] The second holes 42 are instead preferably spaced apart from the first holes 41. They are, in particular, adapted to allow the passage of air or gas. Alternatively, the second holes 42 could coincide with the first holes 41 and house the tubes 11 maintaining a gap externally to them to allow the passage of air or gas.

[0073] In general, the second holes 42 also extend parallel to the dispensing direction 4a. Therefore, substantially, the first holes 41 are adapted to house part of the stem of the tubes 11. The second holes 42, at the same time, are adapted to allow the passage of air or gas.

[0074] The group 4' also comprises a slit 43.

[0075] The slit 43 extends transversely to the dispensing direction 4a between the first holes 41 and the second holes 42. In other words, the acceleration conduits 40 and the second holes 42 are connected by the tubes 11 and separated by the slit 43 which is transverse to the tubes 11 themselves. Then, the slit 43 is in fluid passage connection with the second holes 42.

[0076] Advantageously, the slit 43 extends in the group 4' from side to side. This means that the slit 43 extends, in a plane transverse to the dispensing direction 4a, the slit 43 starts from an opening on one side of the group 4' and ends at an opening on an opposite side of the group 4'.

[0077] Hence, the distributor 2 advantageously comprises a housing 22. The housing 22 is substantially a groove made in the support 2 extending along the longitudinal direction 1b.

[0078] The housing 22 is also preferably open along at least one side along the longitudinal direction 1b so that the spinneret 4 can be removed and inserted by sliding, preferably along the longitudinal direction 1b and along the side comprising said opening. Said opening is also preferably reclosable by closing means such as, for example, a plate reclosable by interlocking or sliding in a direction perpendicular to the longitudinal direction 1b, or the like.

[0079] The housing 22 is configured to contain the spinneret 4. Therefore, the distributor 2 substantially embraces the spinneret 4 when the latter is in use in the plant 1. The spinneret 4 substantially acts as an insert or cartridge that can be inserted into the support 2. Preferably, therefore, the secondary access 21 is in fluid passage connection with the housing 22 by means of conduits extending transversely to the dispensing direction 4a and in particular to the longitudinal direction 1b.

[0080] Thus, the slit 43 is in fluid passage connection with the secondary access 21 and is also configured to convey air or gas from the secondary access 21 to the second holes 42.

[0081] The plant 1, in addition to what has been described, could further include a jig 5. In particular, the dispenser 3 comprises the jig 5. The jig 5 is in fact adapted to receive the gas to guide the polymeric filaments exiting the dispenser 3, preferably downstream of the spinneret 4.

[0082] The jig 5 is mostly similar to a common outer air plate with some differences.

[0083] The jig 5 is preferably removably constrained to one or more of the distributor 2 and the spinneret 4. Preferably, the jig 5 is removably constrained to the support 2, for example, by constraint means known per se. Then, the jig 5 acts as a cap that traps the spinneret 4 in the housing 22 inside the distributor 2.

[0084] Preferably, the jig 5 preferably includes, for each group 4' one or more, a plurality of third holes 50.

[0085] The third holes 50 are preferably centered with respect to the first holes 41.

[0086] Furthermore, they are adapted to house part of the tubes 11, coming from the first holes 41 of a spinneret 4 and communicating with the second holes 42. Thus, the third holes 50 house part of the tubes 11 and, at the same time, allow the passage of air or gas around the tubes 11. In other words, the third holes 50 are also in fluid passage connection with the second holes 42. To achieve this characteristic, it is sufficient that the third holes 50 are oversized with respect to the tubes 11 in such a way as to create a gap around the tubes 11 for the passage of air.

[0087] The jig 5 further also comprises a seat 51.

[0088] The seat 51 is advantageously configured to partially accommodate the spinneret 4 or at least one group 4'. In this way, the jig 5 can be anchored to the spinneret 4.

[0089] In detail, preferably, the seat 51 is delimited by two edges 51a. The two edges 51a are advantageously positioned on opposite sides with respect to the dispensing direction 4a. Hence, they extend parallel to the dispensing direction 4a and preferably extend parallel to the longitudinal direction 1b. Thus, the seat 51 also extends globally parallel to the longitudinal direction 1b.

[0090] The spinneret 4, or each group 4', therefore comprises at least two slots 48. The two slots 48 are advantageously configured to house the edges 51a. Then, when the spinneret 4' is placed on the jig 5, or vice versa, the edges 51a are substantially introduced into the slots 48 so that the spinneret 4 is anchored to the jig 5.

[0091] The slots 48 extend in the spinneret 4, in each group 4', preferably parallel to the dispensing direction 4a at the ends through which the slit 43 passes.

[0092] The edges 51a, in addition, preferably define a shape converging with respect to the dispensing direction 4a and suitably opposite to the direction of advancement of the filaments. This shape advantageously facilitates its introduction into the slots 48 and, therefore, also facilitates the alignment of the third holes 50 with the tubes 11 when the plant 1 is being assembled, for example.

[0093] The spinneret 4 preferably comprises further features.

[0094] Advantageously, in fact, the spinneret 4 further comprises one or more chosen from a further group 4' and at least one cusp 4".

[0095] If there is an additional group 4', it is distinct, separate and side by side with the other group 4'. Then, the jig 5 can be provided with third holes 50 within which the tubes 11 of the further group 4" are also housed. Or, the jig 5 may include two distinct and separate portions, including third holes 50, adapted to interface with a respective group 4'.

[0096] If a cusp 4" is present, it is flanked by the group 4' and comprises at least one main outlet 40a suitably barycentric to the cusp 4" and therefore incident to the tip of the cusp 4".

[0097] The main outlet 40a is configured to convey polymeric fluid parallel to said dispensing direction 4a.

[0098] Then, if the cusp 4" is present, the spinneret 4 further comprises a pair of secondary outlets 41a.

[0099] The secondary outlets 41a are preferably arranged at opposite sides relative to the cusp 4". Furthermore, the secondary outlets 41a are configured to convey the gas towards the jig 5.

[0100] The jig 5, if the cusp 4" is present, preferably includes an air blade 52. The air blade 52 is substantially adapted to convey air or gas towards the tip of the cusp 4". Then, the air blade 52 defines an outlet 52a.

[0101] The outlet 52a is preferably in fluid passage connection with the secondary outlets 41a. Furthermore, the outlet 52a develops parallel to the dispensing direction 4a at the main outlet 40a.

[0102] Then, the plant 1 comprises, in addition, a transfer device 6.

[0103] The transfer device 6 is advantageously configured to place in fluid passage connection at least one secondary access 21 with two opposite ends of the slit 43 of one group 4' and another secondary access 21 with two opposite ends of the slit 43 of another group 4' or with the pair of secondary outlets 41a.

[0104] Furthermore, in one embodiment, the transfer device 6 can also be advantageously configured to place in fluid passage connection the main access 20 with the acceleration conduits 40 of each group 4' and / or the main outlet 40a.

[0105] Or, alternatively, the distributor 2 may comprise a plurality of main accesses 20. Then, the transfer device 6 may also be configured to place in fluid passage connection a main access 20 with the acceleration conduits 40 of one group 4' and another main access 20 with the acceleration conduits 40 of another group 4' or with the main outlet 40a.

[0106] Then, the transfer device 6 makes it possible to use at least part of the traditional plants for conveying polymeric fluid and gas to the dispenser 3, in particular to the spinneret 4, of the plant 1.

[0107] More in detail, the transfer device 6 comprises at least one main inlet 60.

[0108] The main inlet 60 is in fluid passage connection with the main access 20. Thus, the main inlet 60 is adapted to receive polymeric fluid from the main access 20. Further, the transfer device 6 comprises a plurality of main branches 61.

[0109] The main branches 61 are all in fluid passage connection with the main inlet 60. Furthermore, each of the main branches 61 is in fluid passage connection with the acceleration conduits 40 of a respective group 4' and / or a respective main outlet 40a.

[0110] Then, the main branches 61 transfer polymeric fluid from the main inlet 60 to acceleration conduits 40 and possibly main outlets 40a.

[0111] The transfer device 6 advantageously also comprises a plurality of secondary inlets 62.

[0112] Each of the main inlets 62 is in fluid passage connection with a respective secondary access 21. Then, each main inlet 62 receives gases, e.g. air, from a secondary access 21. Further, the transfer device 6 comprises a plurality of secondary branch pairs 63.

[0113] In each pair, all the secondary branches 63 are in fluid passage connection with a respective secondary inlet 62. Furthermore, in the same pair, each of the secondary branches 63 is in fluid passage connection with a respective end of said slit 43 of a group 4' and / or a secondary outlet 41a of a pair of secondary outlets 41a.

[0114] In order to realize such configurations, in a preferred but not exclusive embodiment shown in Figs. 1-4, the transfer device 6 may be entirely comprised in the distributor 2.

[0115] In this context, therefore, the main inlet 60 preferably corresponds to the main access 20 and each secondary inlet 62 corresponds to a respective secondary access 21.

[0116] Then, the spinneret 4 may comprise, for each group 4', a first main dispensing channel 44. The first main dispensing channel 44 is configured to place in fluid passage connection a main branch 61 and the acceleration conduits 40.

[0117] Then, the spinneret 4 may comprise, for each group 4', a pair of first secondary dispensing channels 45. The first secondary dispensing channels 45 are preferably each configured to place in fluid passage connection a respective secondary branch 63 of a same pair of secondary branches 63 with a respective slit 43 end.

[0118] Furthermore, the spinneret 4 may comprise, for each cusp 40, a main dispensing channel 46 and a pair of secondary dispensing channels 47.

[0119] The main dispensing channel 46 is preferably configured to place in fluid passage connection a main branch 61 and the main outlet 40a.

[0120] Each of the secondary dispensing channels 47 of the pair is configured to place in fluid passage connection a respective secondary branch 63 with a respective secondary outlet 41a of a same said pair of secondary outlets 41a.

[0121] In this embodiment, therefore, the spinneret 4 defines conventional characteristics. The distributor 2 can be in a single piece, or divided into two different blocks.

[0122] For example, the distributor 2 may comprise a support plate and a breaker plate. The support plate, as known, is an interface element normally arranged between cassette 10 and breaker plate. The breaker plate is a connecting plate between the support plate and the spinneret 4.

[0123] Advantageously, the transfer device 6 may be entirely comprised in one or more of the support plate and the breaker plate. This means that the transfer device 6 can be developed in only one of the support plate and the breaker plate, or it can be developed partly in the support plate and partly in the breaker plate.

[0124] As already explained, the description is made considering a section of the plant normal to the main direction 1a.

[0125] However, the plant 1 also develops along the longitudinal direction 1b.

[0126] Therefore, the plant 1 can define a longitudinal plane 1c along which at least part of the plant 1 develops, in particular distributor 2 and dispenser 3.

[0127] The longitudinal plane 1c is parallel to the longitudinal direction 1b. Moreover, even more in detail, the longitudinal plane 1c is a virtual or even physical interface plane accessed by the ends of main 61 and secondary 63 branches.

[0128] In detail, each of the main branches 61 defines a main end 61a.

[0129] The main end 61a is substantially opposite the main inlet 60.

[0130] Each of the secondary branches 63 defines, instead, a secondary end 63a. The secondary end 63a is preferably opposite the secondary inlet 62.

[0131] Then, the ends 61a, 63a are distributed on the main plane 1b in such a way that, for each group 4' or said cusp 4 " and for each set including a main end 61a and a pair of adjacent secondary ends 63a, at least the secondary ends 63a are mutually misaligned with respect to directions normal to the longitudinal direction 1b, as shown in Fig. 5a.

[0132] Alternatively, all the ends 61a, 63a may be mutually misaligned with respect to directions normal to the longitudinal direction 1b, as shown in Fig. 5b.

[0133] In other words, the ends 61a, 63a that are upstream of a same group 4' or cusp 40 and that are adjacent to each other belong to the same set.

[0134] Even more in detail, preferably, for each said group 4' or cusp 4" and for each set, at least one main end 61a and one secondary end 63a of the same group are mutually aligned along development directions 6a. The development directions 6a are transverse to the main direction 1a.

[0135] Furthermore, the development directions 6a are preferably mutually parallel, as explicitly shown in Fig. 5b.

[0136] This configuration advantageously prevents the branches 61, 63 from intersecting with each other.

[0137] In conclusion, the plant 1 can define further detailed characteristics.

[0138] For example, the spinneret 4 may comprise at least one seat 49.

[0139] If present, the seat 49 is configured to house at least one filter 12. The filter 12 can be a spongy element adapted to filter the polymeric fluid entering the spinneret 4. Therefore, the seat 49 is preferably arranged adjacent to the distributor 2.

[0140] In particular, the seat 49 can be arranged between each said main branch 61 and a respective main dispensing channel 44, 46.

[0141] The plant 1 may, of course, also comprise the filter 12 and the cassette 10.

[0142] The operation of the multi-row coaxial melt-blown type plant 1 described above in structural terms is substantially similar to the operation of any multi-row coaxial melt-blown type plant.

[0143] However, the multi-row coaxial melt-blown type plant 1 allows a plurality of rows to be made parallel to each other and to the dispensing direction 4a due to the fact that it can exploit a plurality of groups and / or cusps side by side.

[0144] The multi-row coaxial melt-blown type plant 1 according to the invention achieves important advantages.

[0145] In fact, the multi-row coaxial melt-blown type plant 1 allows more than a single row of polymeric filament to be made. The possibility of using a plurality of groups and / or cusps side by side makes it possible to improve the quality of the nonwoven fabric and increase production speed.

[0146] In addition, the multi-row coaxial melt-blown type plant 1, compared with the aforementioned advantages, makes it possible to reduce the number of components necessary for dispensing a plurality of rows and also makes it possible to exploit at least part of the plants of the prior art since the device can include at least conventional cassettes, and possibly also conventional distributors 2.

[0147] Therefore, the plant 1 makes it possible to reduce the conversion costs of the plants and is, in any case, cheaper both from an operational and maintenance point of view.

[0148] In addition, the plant 1 makes it possible to avoid axial losses between the tubes that can be housed in part of the diffusion device and the holes made on the components of the plant since the cleaning of the spinneret 4 can be carried out from the sides, through the slot 43, without the need to remove the tubes 11 from the first holes 41 as, instead, happens in the plants of the prior art.

[0149] In addition, the plant 1 is easily convertible for the realization of different types of nonwoven fabrics since the conversion can be completed simply by replacing the spinneret inside the housing 22.

[0150] Variations may be made to the invention that fall within the scope of the inventive concept defined in the claims.

[0151] In this context, all the details can be replaced by equivalent elements and any materials, shapes and dimensions can be used.

Claims

1. Multi-row coaxial melt-blown type plant (1) comprising: - a distributor (2) configured to be operatively connected to a cassette (10) and including - at least one main access (20) - adapted to be placed in fluid passage connection with a main conduit (10a) of said cassette (10) and - adapted to convey polymeric fluid and - a plurality of secondary accesses (21) adapted to be placed in fluid passage connection each with a respective secondary conduit (10b) of said cassette (10) adapted to convey gas; - a dispenser (3) in fluid passage connection with said distributor (2), configured to dispense polymeric filaments from said polymeric fluid and including at least: - a spinneret (4) adapted to form said polymeric filaments removably constrained to said distributor (2) and including at least one group (4') in turn including: - a plurality of acceleration conduits (40) extending parallel to a dispensing direction (4a) comprising tubes (11) in fluid passage connection with said at least one main access (20) and configured to distribute said polymeric fluid, - first holes (41) extending parallel to said dispensing direction (4a), centered with respect to said acceleration conduits (40) along said dispensing direction (4a) and configured to house each part of a respective said tube (11), - second holes (42) extending parallel to said dispensing direction (4a) and adapted to allow the passage of air or gas, and - a slit (43) extending transversely to said dispensing direction (4a) between said acceleration conduits (40) and said first holes (41) in fluid passage connection with said second holes (42), and - a jig (5) adapted to receive said gas to guide said polymeric filaments exiting from said dispenser (3), removably constrained to one or more of said distributor (2) and said spinneret (4) and including, for each of said groups (4'), a plurality of third holes (50) centered with respect to said first holes (41), communicating with said second holes (42) and configured to house part of said tubes (11) and to allow, at the same time, the passage of said air or gas around said tubes (11); characterized in that - said spinneret (4) further comprises one or more chosen from: - a further said group (4') distinct, separate and side by side with the other said group (4') and - at least one cusp (4") side by side with said group (4') and comprising at least one main outlet (40a) configured to convey said polymeric fluid parallel to said dispensing direction (4a); and in that if there is a cusp (4") - said spinneret (4) further comprises a pair of secondary outlets (41a) arranged at opposite sides relative to said cusp (4") and configured to convey said gas towards said jig (5); - said jig (5) includes an air blade (52) defining an outlet (52a) in fluid passage connection with said secondary outlets (41a) and developing parallel to said dispensing direction (4a) at said main outlet (40a), and - said plant (1) comprises a transfer device (6) configured to place in fluid passage connection at least - a said secondary access (21) with two opposite ends of said slit (43) of a said group (4') and - another said secondary access (21) with two opposite ends of said slit (43) of another said group (4') or with said pair of secondary outlets (41a).

2. Plant (1) according to Claim 1, wherein said distributor (2) comprises a plurality of main accesses (20) and said transfer device (6) is configured to place in fluid passage connection said main access (20) with said acceleration conduits (40) of one said group (4') and another said main access (20) with said acceleration conduits (40) of another said group (4') or with said main outlet (40a).

3. Plant (1) according to Claim 1, wherein said transfer device (6) is also configured to place in fluid passage connection said main access (20) with said acceleration conduits (40) of each of said group (4') and / or said main outlet (40a).

4. Plant (1) according to the preceding claim, wherein said transfer device (6) comprises at least one main inlet (60) in fluid passage connection with said main access (20), a plurality of main branches (61) all in fluid passage connection with said main inlet (60) and each with said acceleration conduits (40) of a respective said group (4') and / or a respective said main outlet (40a), a plurality of secondary inlets (62) each in fluid passage connection with a respective said secondary access (21), and a plurality of pairs of secondary branches (63); wherein in each pair said secondary branches (63) is in fluid passage connection with a respective said secondary inlet (62) and each of said secondary branches (63) is in fluid passage connection with a respective end of said slit (43) of a said group (4') and / or a said secondary outlet (41a) of a said pair of secondary outlets (41a).

5. Plant (1) according to any one of the preceding claims, wherein said transfer device (6) is entirely comprised in said distributor (2), said main inlet (60) corresponds to said main access (20), each said secondary inlet (62) corresponds to a respective said secondary access (21), and said spinneret (4) comprises: - for each said group (4'), a first main dispensing channel (44) configured to place in fluid passage connection said main branch (61) and said acceleration conduits (40) and a pair of first secondary dispensing channels (45) each configured to place in fluid passage connection a respective said secondary branch (63) of a same said pair of secondary branches (63) with a respective said end of said slit (43), and / or - for said cusp (4"), a second main dispensing channel (46) configured to place in fluid passage connection said main branch (61) and said main outlet (40a) and a pair of second secondary dispensing channels (47); wherein each of said second secondary dispensing channels (47) is configured to place in fluid passage connection a respective said secondary branch (63) of a same said pair of secondary branches (63) with a respective said secondary outlet (41a) of a same said pair of secondary outlets (41a).

6. Plant (1) according to the preceding claim, wherein said distributor (2) comprises a support plate and a breaker plate; and wherein said transfer device (6) is entirely comprised in one or more of said support plate and said breaker plate.

7. Plant (1) according to any one of the preceding claims, wherein said distributor (2) and said dispenser (3) develop mainly along a longitudinal direction (1b); wherein each of said main branches (61) defines a main end (61a) opposite to said main inlet (60); wherein each of said secondary branches (63) defines a secondary end (63a) opposite to said secondary inlet (62); and wherein said ends (61a, 63a) are distributed on a longitudinal plane (1c) parallel to said longitudinal direction (1b) in such a way that, for each said group (4') or said cusp (4") and for each set including a said main end (61a) and a pair of said adjacent secondary ends (63a), at least said secondary ends (63a) are mutually misaligned with respect to directions normal to said longitudinal direction (1b).

8. Plant (1) according to the preceding claim, wherein said ends (61a, 63a) are distributed on a longitudinal plane (1c) in such a way that all said ends (61a, 63a) of the same said group are mutually misaligned with respect to directions normal to said longitudinal direction (1b).

9. Plant (1) according to any one of Claims 7-8, wherein for each said group (4') or said cusp (4") and for each said set, at least one said main end (61a) and one said secondary end (63a) are mutually aligned along development directions (6a) transverse to said main direction (1a).

10. Plant (1) according to any preceding claim, wherein said spinneret (4) comprises at least one seat (49) configured to house at least one filter (12) and arranged adjacent to said distributor (2).

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