HK1187385A - Process and apparatus for spinning fibres and in particular for producing a fibrous-containing nonwoven - Google Patents

Abstract

The apparatus (1) is used for producing meltblown fibres (MF). It comprises a die head (104) with several spinning orifices, means (100, 101,102, 103) for extruding at least one melted polymeric material through the spinning orifices of the die head (104) in the form of meltblown filaments (f), and means (104a,104b) for blowing a hot primary gas flow (F1) towards the outlet of the die head (104) in order to draw and attenuate the polymeric filaments (f) at the outlet of the die head, and a drawing unit (105) that is positioned below the die head (104), and that is adapted to create an additional gas flow (F3) that is oriented downstream to further draw and attenuate the meltblown filaments (f).

Description

Method and device for spinning fibers, in particular for producing a fiber-containing nonwoven

Technical Field

The present invention relates to the field of fiber weaving. In this field, the invention relates generally to a novel and improved method and apparatus for spinning fibers and to a novel method and apparatus for producing fiber-containing nonwovens, and particularly pulp-containing meltblown nonwovens.

Background

A well-known technique for spinning fibers and making nonwoven fabrics is the so-called meltblown technique. Methods and apparatus for making meltblown nonwovens are well known and described, for example, in U.S. Pat. No. 3,849,241 to Butin et al and in U.S. Pat. No. 4,048,364 to Harding et al.

Basically, well known processes for making meltblown nonwovens include: extruding (extruding) the molten polymer material through a die (diehead) into melt-blown polymer filaments; and attenuating the filaments by converging a high velocity stream of heated gas (typically air, hereinafter referred to as "primary air"). The primary air is heated at a temperature typically equal to or slightly above the melting temperature of the polymer. The hot primary air draws (draw) and attenuates the polymer filaments immediately at the exit of the die. In the melt-blown process, the drawing force for attenuating the melt-blown filaments is thus applied at the outlet immediately adjacent to the die while the polymer is still in the molten state. At the outlet of the die, a large amount of cooling air (hereinafter referred to as "secondary air") is drawn into the primary air. The secondary air cools down the meltblown filaments downstream of the die head and provides quenching of the meltblown filaments.

Typically, in the meltblown process, the primary air is also conditioned in such a way that the meltblown filaments break into discontinuous fibers (microfibers or nanofibers) of shorter length at the exit of the die. The discontinuous fibers generally have a length that exceeds the typical length of staple fibers. More particularly, discontinuous meltblown fibers having a length between 5mm and 20mm can be produced so far using standard known meltblowing processes.

The meltblown fibers are carried from downstream of the die to a moving surface such as, for example, a rotating drum (cylinder) or a conveyor belt, to form a meltblown nonwoven web of unoriented meltblown fibers. Preferably, the forming surface is air permeable and even more preferably suction means are provided for sucking the fibres onto the forming surface. The meltblown nonwoven web may then be conveyed to a consolidation means (consolidation means) such as, for example, a thermal bonding calender, a water needling unit, an ultrasonic bonding unit, to form a consolidated meltblown nonwoven web.

Meltblown nonwovens made from very fine denier fibers can be advantageously produced using standard meltblowing processes. Typically, the average diameter of the meltblown fibers may be less than 10 μm. Thus, a meltblown nonwoven with low air permeability and good coverage can be advantageously obtained.

In return, melt blowing technology has several limitations and disadvantages.

During the standard melt blowing process, the melt blown fibers are subjected to only small elongations and the melt blown fibers thus exhibit low tenacity. Meltblown fibers therefore generally have poor mechanical properties and in particular exhibit low tenacity, low elasticity and low mechanical tensile strength in the machine direction and cross direction.

In addition, in standard meltblowing processes, the velocity of the primary air must be adjusted in order to achieve the desired attenuation of the meltblown filaments and to properly break the meltblown filaments into discrete meltblown fibers having a predetermined average length. In fact, to achieve sufficient attenuation of the meltblown filaments and produce fine meltblown fibers, the velocity of the primary air must be sufficiently high, which also results in the production of shorter meltblown fibers. In standard meltblowing processes, adjustment of the average diameter and length of the meltblown fibers is thus difficult and less flexible. In particular, it is difficult to produce melt blown polypropylene fibers having very small diameters (typically less than 10 μm) and having long lengths (typically greater than 20 mm), for example.

To date, only polymers of high melt index (typically between 600 and 2000) have been processed in standard melt blowing techniques. Even with spinnerets having non-circular textile apertures (and, for example, double lobed apertures), this high melt index in combination with the drawing of the filaments results in a deformation of the cross-section of the filaments and the shape of the filaments imparted by the textile apertures cannot be maintained. In practice, it is possible to produce meltblown filaments which have only a substantially circular cross section.

In us patent 5,075,068 it is proposed to discharge additional cross-flow air towards the meltblown filaments to disrupt their shape by creating waves in the filaments. This fluctuation will increase the drag imparted by the primary meltblown air. To the best of the inventors' knowledge, this technique has never been commercialized, and the generation of the wire wave by cross-flow air seems to be difficult to control and may lead to an unfavorable wave of the wire.

The consolidated meltblown nonwoven can be used alone for the manufacture of a textile product or can be used in a laminate comprising additional layers, such as, for example, other nonwoven webs (meltblown web, spunbond web, carded web, airlaid) and/or additional fiber layers, such as, for example, fiber layers made of wood pulp fibers, and/or additional plastic films. The laminate can be consolidated by any known consolidation means, including thermal, mechanical, hydro-needling, ultrasonic, breathable, and adhesive bonding.

More particularly, in order to produce laminates with high absorption properties, it is known to laminate at least one layer of fibrous material with high absorption capacity, such as for example a layer of short wood pulp fibers, with a meltblown nonwoven. The layer of wood pulp fibers may also be mixed with particles, such as particles made of superabsorbent material.

A serious disadvantage of such laminates is the low cohesion between the fibrous layers and the meltblown nonwoven before or even after the consolidation step of the laminate. This low cohesion results in high and undesirable loss of fibrous material (e.g., wood pulp fibers).

A process for producing fiber-containing meltblown nonwovens, and more particularly pulp-containing meltblown nonwovens, is also known in the art and is disclosed, for example, in U.S. patent No. 4,931,355 and U.S. patent No. 4,939,016 to Radwanski et al. Fibrous material (e.g., wood pulp) is fed directly into the polymer stream immediately downstream of the outlet of the meltblowing die.

In such a process, it is practically difficult to reliably incorporate the fibrous material inside the meltblown filaments extruded through the die due to the high velocity of the polymer stream at the exit of the die. Thus, during the manufacturing process, a significant amount of fibrous material is not incorporated into the meltblown filaments and instead is pushed back by the gas stream surrounding the meltblown filaments downstream of the die head. In addition, in the fiber-containing meltblown nonwoven obtained by this method, the fiber material is not sufficiently mixed with the meltblown fibers, and the bondability of the fiber material and the meltblown fibers is low. This low bonding results in high loss of fibrous material when the fibrous containing meltblown nonwoven is subsequently conveyed or treated. Such loss of fibrous material is even more severe and disadvantageous when the meltblown nonwoven containing fibers is subjected to a subsequent hydraulic needling step, as described in the above-mentioned U.S. patent No. 4,931,355 and U.S. patent No. 4,939,016.

Summary of the invention

A first object of the present invention is to propose a novel and improved solution for spinning meltblown fibers.

This first object is achieved by the melt blowing apparatus of claim 1 and the melt blowing method of claim 11.

An apparatus for producing meltblown fibers comprising: a die having a plurality of spinning apertures; means for extruding at least one molten polymeric material through the spinning orifices of the die into the form of meltblown filaments; and means for blowing a hot primary gas stream towards the outlet of the die to draw and attenuate the polymer filaments at the outlet of the die; and a drawing unit positioned below the die head and adapted to generate additional gas streams directed downstream for further drawing and attenuating the meltblown filaments.

The method comprises the following steps:

(i) extruding at least one molten polymeric material through the spinning orifices of a die to form polymeric meltblown filaments,

(ii) the meltblown filaments at the exit of the die are drawn and attenuated by a stream of hot primary air,

(iii) a drawing unit positioned below the die head for generating additional gas streams directed downstream is used to further draw and attenuate the meltblown filaments.

A second object of the present invention is to propose a novel and improved solution for manufacturing fibrous-containing non-woven fabrics which significantly overcomes the above-mentioned drawbacks of the solutions disclosed in U.S. patent No. 4,931,355 and U.S. patent No. 4,939,016 to Radwanski et al.

This second object is achieved by a weaving device as claimed in claim 23 and a weaving method as claimed in claim 37.

A textile apparatus for making a fibrous-containing nonwoven comprising: a die having a plurality of spinning apertures; means for extruding at least one molten polymeric material through the spinning orifices of the die into the form of meltblown filaments; and a drawing unit positioned below the die head and adapted to generate an additional gas stream directed downstream for drawing and attenuating the meltblown filaments, the apparatus further comprising a supply device for continuously feeding a stream of fibrous material at a location between the die head and the drawing unit and adjacent to the filaments.

The textile process for manufacturing a fibrous-containing non-woven fabric comprises the following operations:

(i) extruding at least one molten polymeric material through the spinning orifices of a die to form polymeric filaments,

(ii) using a drawing unit positioned below the die head for generating a gas flow directed downstream for drawing and attenuating the filaments,

(iii) the fibrous material is continuously fed at a location between the die head and the drawing unit and adjacent to the filaments.

A third object of the invention is to propose a novel and improved solution for weaving discontinuous fibres.

This third object is achieved by an apparatus as claimed in claim 51 and a method as claimed in claim 64.

An apparatus for weaving discontinuous fibers comprising: a die having a plurality of spinning apertures; means for extruding at least one molten polymeric material through the spinning orifices of the die into a meltblown form; and a drawing unit positioned below the die head and adapted to generate a gas flow (F3) directed downstream for drawing and attenuating the filaments (F) and for breaking the filaments into discontinuous fibres.

In a method for manufacturing discontinuous fibers (MF):

(i) extruding at least one molten polymeric material through the spinning orifices of a die to form polymeric filaments,

(ii) a drawing unit positioned below the die head is used for generating a downstream directed gas flow for drawing and attenuating the filaments in such a way as to break them into discontinuous fibers.

The word "fiber" as used herein and in the claims includes both long continuous fibers (also commonly referred to as "filaments") and shorter discontinuous fibers.

The word "downstream" as used herein and in the claims means that the gas stream is oriented generally in the direction of the polymer stream.

Another object of the invention is a non-woven fabric comprising at least one layer of non-staple fibers having a shaped cross-section and having an average length not exceeding 250 mm.

More particularly, the layer also comprises fibrous material mixed with non-staple fibers.

The fibrous material may advantageously comprise absorbent pulp fibres.

The expression "non-staple fibers" as used herein and in the claims defines discontinuous fibers which have been obtained by drawing polymeric filaments in such a way as to break them during their extrusion, in contrast to the so-called "staple fibers" which are obtained by mechanical cutting of the filaments mainly by means of a cutting blade after their extrusion process.

The staple fibers are generally of the same length and are pre-crimped (crimp) prior to cutting. In contrast, non-staple fibers have different lengths due to random breaks during their extrusion and are generally not crimped.

The words "shaped fiber" or "shaped cross-section" as used herein and in the claims refers to a fiber having a non-circular cross-section.

It is another object of the invention to use the nonwoven to make absorbent products, and more particularly dry or wet wipes, diapers, training pants, sanitary napkins, incontinence products or mattresses.

Brief description of the drawings

Other characteristics and advantages of the present invention will become clearer when reading the following description of a preferred embodiment thereof, given by way of non-limiting example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of an apparatus according to a first embodiment of the invention and suitable for producing novel fiber-containing meltblown nonwovens,

FIG. 2 is a cross-sectional detail of an example of an air-drawing unit that can be used in the apparatus of FIG. 1,

FIG. 3 is a cross-sectional view of a double-lobed meltblown fiber,

FIG. 4 is a cross-sectional view of a trilobal meltblown fiber,

FIGS. 5A to 5C are schematic views of a production line suitable for producing a laminate comprising several meltblown non-woven fabrics of the invention,

figure 6 is a schematic view of an apparatus according to a second embodiment of the invention and suitable for producing a fibrous-containing non-woven fabric.

Detailed Description

Referring to fig. 1, the apparatus 1 comprises a melt blowing apparatus 10 for spinning polymer melt blown fibers MF and a conveyor belt 11 for receiving the melt blown fibers MF discharged from the melt blowing unit 10. The conveyor belt 11 is air-permeable and is known to be associated with suction means 12 for sucking the meltblown fibers MF onto the surface 11a of the conveyor belt 11. In operation, the surface 11a of the conveyor belt 11 is moved in the machine direction MD in such a way that a meltblown nonwoven web MBW is formed on the surface 11a at least by meltblown fibers MF randomly deposited on the surface 11 a.

As is known in the art, the meltblowing apparatus 10 includes:

-an extruder (100) for extruding a mixture of,

a hopper 101 containing polymer particles P, said hopper 101 being connected to the extruder 100 and adapted to supply the extruder 100 with polymer particles P by gravity,

a textile pump 102 connected to the outlet of the extruder via a conduit 103,

a meltblowing die 104, known to comprise: parallel row or rows of textile apertures extending in the transverse direction (perpendicular to the direction of fig. 1); and blowing means 104a, 104b for converging a flow of heated air F1 (hereinafter referred to as "hot primary air") towards the outlet of the die 104 formed by the textile orifices.

These components 100 to 104 of the meltblowing apparatus 10 are known in the art and will not be described in detail.

In operation of the meltblowing apparatus 10, polymer pellets P are melted by an extruder 100 into molten polymer material, which is fed by the extruder 100 to a textile pump 102. The textile pump 102 feeds the die 104 to extrude molten polymer material through the textile orifices of the die 104 and form a vertical curtain (curl) of polymer melt filaments f at the exit of the die 104. This vertical curtain of polymer melt filaments f extends in a transverse direction perpendicular to the plane of fig. 1.

While the polymer is still in the molten state, the hot primary air (hot air stream F1) draws and attenuates the molten filaments F immediately at the exit of the die head 104. This hot primary air F1 is typically heated at a temperature substantially equal to or slightly above the melting temperature of the polymer. At the outlet of the die, a large amount of cooling air (air flow F2, hereinafter referred to as "secondary air") is drawn into the primary air. The secondary air F2 cools down the polymer filaments F downstream of the die head 104 and provides quenching of the polymer meltblown filaments F.

The meltblowing apparatus 10 comprises in a novel manner an additional air-drawing unit 105 positioned below the die head 104 and adapted to further draw and attenuate the polymeric meltblown filaments f.

Preferably, but not necessarily, the distance d between the outlet of the die head 104 and the inlet of the air-drawing unit 105 is adjustable.

Fig. 2 shows a specific embodiment of a suitable air-drawing unit 105. However, the present invention is not limited to the specific configuration of FIG. 2 and includes any drawing unit that can be used to continuously draw and attenuate the polymer meltblown filaments f, particularly with a gas stream.

Referring to the particular embodiment of fig. 2, the drawing unit 105 comprises a vertical channel 1050 having an upper longitudinal slot inlet 1050a and a lower longitudinal slot outlet 1050b, both extending in the transverse direction (perpendicular to the direction of fig. 2). This channel 1050 is vertically aligned with the outlet (row of spinning orifices) of the die head 4 in such a way that the curtain of meltblown filaments f passes through the channel 1050. On each side of the channel 1050, the drawing unit 105 comprises a succession of four chambers 1051, 1052, 1053, 1054, which communicate via longitudinal slit openings 1051a, 1052a, 1053 a. The last chamber 1054 communicates with the channel 1050 via a longitudinal slot outlet 1054 a. The first chamber 1051 houses a longitudinal blowing duct 1055 comprising a longitudinal slot outlet 1055 a.

In operation, the blowing duct 1055a is supplied with gas, and more particularly air, under pressure at ambient temperature. This air is discharged into the chamber 1051 via the slot outlet 1055a and then passes through the chambers 1052, 1053 and 1054 in series. This air under pressure is discharged into the passageway 1050 via slot outlet 1054a in the form of a high velocity downward air flow F3. Each slot outlet 1054a is inclined in such a way that the air flow F3 is directed downstream of the filaments F and substantially in the longitudinal direction of the filaments, i.e. substantially in the same longitudinal downstream direction as the polymer flow forming the filaments F.

In operation, the polymeric meltblown filaments F pass through the channels 1050 of the drawing unit 105 and are drawn and attenuated by air streams F3 (fig. 2) which are blown at ambient temperature into the channels on each side of the curtain of meltblown filaments F, generally in the longitudinal direction of the filaments F. These air flows F3 also cool down the filaments F and thus contribute to the solidification (quenching) of the filaments F.

The high velocity air flow F3 also creates air suction above the drawing unit 105 by the venturi effect. This air suction creates an additional air flow F4 which is drawn into the channel 1050 via the inlet 1050a and assists in the cooling and solidification of the filaments F.

In the drawing unit 105, the air flow does not generate turbulence that would impart an oscillation or would generate a wave in the filaments. In the drawing unit 105, the wire remains straight and does not have any oscillation.

The velocities of the air streams F1 (die head 104) and F3 (drawing unit 105) may advantageously be selected in such a way that the filaments F break at the outlet 1050b of the drawing unit 105 and form discontinuous meltblown fibers MF having a predetermined average length (fig. 2).

The velocities of the air streams F1 and F3 may advantageously be adjusted individually, which increases the flexibility of the setup of the meltblowing apparatus 10.

More particularly, in the present invention, the distance between the drawing unit 105 and the outlet of the die 104 can be adjusted to break the filaments f and form discontinuous non-staple fibers having a specific average length. Preferably, the distance between the drawing unit 105 and the outlet of the die 104 can be adjusted to break the filaments f and form discontinuous non-staple fibers having an average length not less than 20mm (preferably greater than 40 mm) and not greater than 250mm (and preferably not greater than 150 mm).

Due to the use of this additional drawing unit 105, the drawing energy of the polymer chains of the filaments f is greater than what is usual in standard meltblowing equipment, which advantageously enables to increase the tenacity of the meltblown fibers MF and thus the tenacity and the MD (machine direction) tensile strength of the meltblown nonwoven web MBW comprising such fibers.

In the present invention, the air-drawing unit 105 can be used and adjusted to produce very fine denier fibres MF having an average diameter of less than 10 μm and preferably less than 2 μm, but can also be advantageously used and adjusted to produce coarser discontinuous non-staple fibres MF having an average diameter of not less than 10 μm and preferably between 10 μm and 400 μm.

In another variant of the invention, the speed of the air flows F1 (die head 104) and F3 (drawing unit 105) can also advantageously be chosen in such a way that the filaments F of the drawing unit 105 are not broken at the outlet 1050b and thus form the continuous meltblown fibers MF.

Due to the use of the air-drawing unit 105, the polymer used to make the filaments may advantageously have a low melt index, and in particular a melt index (ASTM D1238) between 15 and 70. Shaped fibres having a non-circular cross-section but having, for example, a multilobal cross-section and in particular a bilobal cross-section can thus be spun.

In the embodiment of fig. 1, the apparatus 1 further comprises a supply device 13 for feeding a stream of fibrous material FM at a position between the die head 104 and the drawing unit 105, so that the fibrous material FM is continuously incorporated in the curtain of polymeric meltblown filaments f extruded from the die head 104.

The term "fibrous material" as used herein and in the claims encompasses any material comprising short length fibers and/or comprising particles.

The average length of the fibers of the fibrous material FM will generally not exceed the average length of the meltblown fibers MF. However, for fibrous materials, fibers having an average length greater than the MF length of the meltblown fibers may also be used.

More particularly, the fibrous material may advantageously comprise "pulp".

The term "pulp" as used herein and in the claims refers to an absorbent material made from or comprising fibers from natural sources, such as woody or non-woody plants. Woody plants (i.e., wood pulp) include, for example, deciduous trees and coniferous trees. Nonwoody plants include, for example, cotton, flax, thatch, milkweed, straw, jute, and bagasse. Typically, the average length of the pulp fibres does not exceed 5 mm. However, for the fibrous material FM, longer fibers may also be used.

Within the scope of the invention, the fibrous material may be made of pulp alone or may also be made of a dry mixture of pulp and other materials (fibers and/or particles). In particular, the fibrous material may comprise a dry mixture of pulp and superabsorbent material (SAM) particles.

The fibrous material may also comprise staple fibers (natural and/or man-made) and is for example cotton fibers.

In the particular embodiment of fig. 1, the supply device 13 comprises a vertical duct (chimney) 130 pneumatically fed with the fibrous material FM in its upper part. In the lower part of the duct 130, the supply device 13 comprises two counter-rotating feed rollers 131, 132 extending longitudinally in transverse direction substantially over the entire width of the duct 130. The lower roller 132 is provided with teeth 132a on the entire periphery thereof.

The supply device 13 further comprises a blowing device 134 comprising a longitudinal slot outlet 134a extending in the transverse direction substantially over the entire width of the duct. The blowing device 134 is adapted to blow compressed air through the outlet 134 a.

The supply device 13 further includes a feed nozzle 133 positioned below the feed roller 132. The nozzle 133 has an outlet 133a for the fibrous material MF. The outlet 133a forms a longitudinal slot and is positioned between the die head 104 and the drawing unit 105 and close to the curtain of meltblown filaments f. This longitudinal slot outlet 133a extends in the transverse direction (perpendicular to the direction of fig. 1) substantially over the entire width of the curtain of meltblown filaments f to feed the fibrous material MF substantially over the entire width of the curtain of meltblown filaments f.

In operation, the fibrous material F is stacked in the duct 130. The compressed air (air flow F5) is continuously discharged by the blowing device 134 via the longitudinal slit outlet 134a inside the nozzle 133. The rollers 131, 132 rotate to continuously supply the fiber material MF to the nozzle 133. The fibrous material MF is carried by the air flow F5 generated inside the nozzle 133 by the blowing means 134. At the outlet 133a of the nozzle 133, the fibrous material MF is continuously conveyed close to the curtain of meltblown filaments f.

Due to the use of the air-drawing unit 105, the fibrous material MF enters into contact with the meltblown filaments f and is carried into the drawing unit 105. In addition, due to the air flow F4 (fig. 2) generated by the drawing unit 105, the fibrous material FM is also sucked into the passage 1050 of the drawing unit 105, wherein the fibrous material FM is intimately mixed with the polymer filaments F.

At the outlet 1050b of the drawing unit 105, the fibrous material FM is advantageously intimately mixed with the meltblown fibers MF and also partly thermally bonded thereto. Thus, a meltblown web MBW containing fibers is formed on the surface 11a of the conveyor belt 11, wherein the mixing and bonding of the fibrous material MF with the meltblown fibers MF is enhanced in comparison to the solutions disclosed, for example, in U.S. Pat. No. 4,931,355 to Radwanski et al and in U.S. Pat. No. 4,939,016. Thus, when the meltblown web MBW containing fibers is subsequently consolidated and/or treated, the loss of fibrous material FM is significantly reduced.

In the present invention, the use of additional drawing unit 105 also enables lower velocity air streams F1 and F2 to be implemented, as compared to standard meltblowing apparatus having only a meltblowing die without additional drawing unit 105, as disclosed, for example, in U.S. patent No. 4,931,355 to Radwanski et al and in U.S. patent No. 4,939,016. By reducing the speed of the air flows F1 and F2, the risk of pushing back the fibrous material FM is advantageously less. Thus, it is advantageously easier to incorporate a larger amount of fibrous material inside the meltblown fibers MF.

In the particular embodiment of FIG. 1, the apparatus 1 further includes a consolidation device 14 positioned downstream of the meltblowing apparatus 10. In this particular example, these pre-reinforcing means 14 consist of thermal bonding units known in the art. The thermal bonding unit 14 is a calender comprising two pressure rollers 14a, 14 b. The lower roller 14b has a smooth surface, such as a rubber surface. The upper roll 14a is a hard steel roll comprising, for example, an engraved surface with protruding ribs which are regularly distributed over the entire surface of the roll and form a bonding pattern. And when the fibrous material suitably comprises thermoplastic fibers, the two rolls 14a, 14b are heated to obtain softening of the surface of the meltblown fibers MF.

In operation, the conveyor belt 11 is used to convey and transfer the fiber-containing meltblown nonwoven web MBW between the two rolls 14a, 14b to pre-consolidate the fiber-containing meltblown nonwoven web by thermal and mechanical compression (thermal bonding).

However, the present invention is not limited to the use of thermal bonding units to consolidate fiber-containing meltblown nonwoven webs MBW, but other consolidation techniques known in the art may be used, such as, for example, mechanical bonding, hydro-needling, ultrasonic bonding, air-through bonding, and adhesive bonding.

The hot primary air F1 can be obtained generally by heating the air using a heat source positioned outside the die 104 as in standard meltblowing processes. In other variations of the invention, however, the heated air can only be heated by the heat generated by the die head 104 as the air passes through the die head 104.

In another variant of the invention, the apparatus of fig. 1 can be modified in such a way that the polymeric material is extruded only in the form of filaments F in the die 104, without generating any hot primary air F1. In this case, only the drawing unit 105 is used to draw and thin the wire f. In this case, the structure of the die 104 can be simplified.

In another variant of the invention, the primary air F1 can be generated at a low speed in such a way that it does not have to be used to draw and attenuate the filaments F at the outlet of the die head 104, but only to clean the die head 104 and avoid broken filaments damaging the weaving holes.

In a further variant of the invention, the apparatus of fig. 1 can be modified in such a way that spun-bonded filaments MF are produced.

The polymer P used for making the fibers MF can be any melt spinnable polymer that can be extruded through a die. Good alternatives are for example polyolefins, in particular homopolymers or copolymers of polypropylene or polyethylene, homopolymers or copolymers of polyesters, homopolymers or copolymers of polyamides or any mixtures thereof. It can also advantageously be any biodegradable thermoplastic polymer, such as for example a homopolymer or copolymer of polylactic acid (PLA), or any biodegradable mixture comprising a homopolymer or copolymer of PLA. In this case, the nonwoven web MBW is advantageously completely biodegradable when the fibrous material is made of a biodegradable material.

The fibers MF will be generally inelastic. However, elastomers or elastic fibers MF may also be used.

The fibers MF may be mono-or multicomponent fibers, in particular bicomponent fibers, and more particularly sheath-core bicomponent fibers. When producing bicomponent fibers, two extruders are used to simultaneously feed each polymer to the die 104.

Various cross-sectional shapes (circular, oval, multilobal, and especially bilobal, trilobal, etc.) can also be implemented for the fibers MF. The cross-sectional shape of the meltblown fibers MF is determined by the geometry of the spinning orifices of the die 104.

However, when multilobal fibers MF are used, especially when double lobal fibers as shown in fig. 3 and generally called "pterocele" fibers are used, or when trilobal fibers as shown in fig. 4 are used, the bonding of the fiber material MF to the fibers is significantly enhanced.

Fig. 5A to 5C show an example of a continuous production line for producing a four-layer laminate consisting of: a bottom spunbond nonwoven web S made by continuous spinning, a first intermediate meltblown web MBW1, a second intermediate fiber-containing meltblown web MBW2, a third intermediate fiber-containing meltblown web MBW3, and a top fiber-containing meltblown web MBW 4.

In particular, the line 2 comprises (fig. 5A) a supply device 20 for continuously supplying a bottom spunbond nonwoven web S onto a conveyor belt 21. In this particular example, these supply means 20 comprise: a storage roll 20a on which the spunbond nonwoven web S is wound; and a motorized roller 20b associated with the storage roller 20a and adapted to continuously unwind the spunbond nonwoven web S from the storage roller 20a and place the spunbond nonwoven web S on the conveyor belt 21. These supply devices 20 can also be replaced by a spunbond unit adapted to linearly produce a spunbond nonwoven web S made of continuous filaments randomly laid directly on a conveyor belt 21.

Upstream of these supply means 20, the production line 2 comprises a succession of four devices 22, 23 (fig. 5B), 24 and 25 (fig. 5C). The devices 23, 24, 25 are identical to the device 1 described previously with reference to fig. 1. The apparatus 22 is similar to the apparatus 1 of fig. 1, but does not comprise a fibrous material supply.

The first apparatus 22 is used to continuously weave a first meltblown web MBW1 directly onto the spunbond nonwoven web S. The second apparatus 23 is used to continuously weave a second intermediate fiber-containing meltblown web MBW2 directly onto the first meltblown web MBW 1. The third apparatus 24 is used to continuously weave a third fiber-containing meltblown web MBW3 directly onto the second intermediate fiber-containing meltblown web MBW 2. The fourth apparatus 25 is used to continuously weave the fibre-containing meltblown web MBW4 directly onto the third intermediate fibre-containing meltblown web MBW 3.

The laminate MBW4/MBW3/MBW2/MBW1/S is then successively conveyed to a standard thermal bonding unit 26 to thermally bond the different layers of the laminate and obtain a consolidated laminate. The consolidated laminate MBW4/MBW3/MBW2/MBW1/S was then wound linearly on storage roll 27 a.

In a preferred embodiment, the meltblown fibers of the first and fourth meltblown nonwoven webs MBW1 and MBW4 are bilobal or trilobal, and the nonwoven fibers of the second and third meltblown nonwoven webs MBW2 and MBW3 may have any shape, in particular may be round. However, the present invention is not limited to this particular laminate.

More generally, within the scope of the present invention, it may be advantageous to produce a laminate comprising at least one fibrous-containing meltblown web of the present invention, which laminate is laminated with one or more other layers, including in particular spunbond layers, carded layers, meltblown layers, plastic films.

The fibrous meltblown web of the invention or a laminate comprising at least one fibrous meltblown web of the invention can be advantageously used to make absorbent products, and more particularly dry or moist wipes, diapers, training pants, sanitary napkins, incontinence products or bed pads.

Fig. 6 shows another variant of the inventive weaving device 1' that can be used for manufacturing a fibrous non-woven NW.

In this variant, the die 104 'of the weaving device 1' is modified to extrude several rows (three rows in this particular example) of polymeric filaments f, instead of one row for the device of fig. 1. Preferably, in this weaving device 1 ', no primary hot air F1 is generated in the die head 104 ' and the polymer filaments F are extruded only through the weaving holes of the die head 104 '.

A cooling unit 106 is installed below the outlet of the die. Said cooling unit 106 comprises two blowing boxes 106a positioned on each side of the filaments F and adapted to blow several forced transverse air flows F6 towards the filaments F to cool down the filaments F and quench them in a similar way to the quenching air used in standard spunbonding equipment. The temperature of the quenching air F6 is, for example, between 5 ℃ and 20 ℃.

The drawing unit 105, identical to the previously described drawing unit, is used at a position below the cooling unit 106 for generating the same downstream-directed air flow F3 as the previously described air flow F3, which draws and attenuates the filaments F.

All previous descriptions made above in connection with the drawing unit 105 of the first embodiment of fig. 1 (and in particular in connection with the use of this drawing unit 105 for breaking the filaments f into discontinuous non-staple fibers MF) also apply to the second embodiment of fig. 6, and these descriptions will not be repeated.

In the particular embodiment of fig. 6, a fibrous material supply device 13' is also provided. The fibre material supply device 13' also comprises a vertical duct 130, which is pneumatically supplied with fibre material FM in its upper part. In the lower part of the duct 130, the supply device 13' comprises two counter-rotating feed rollers 131, 132 extending longitudinally in transverse direction substantially over the entire width of the duct 130. The lower roller 132 has teeth 132a on the entire periphery thereof.

The supply device 13 'also comprises a feed channel 133' positioned below the feed roller 132. The supply channel 133' has an outlet 133a for the fibrous material MF. Said outlet 133a forms a longitudinal slit and is positioned between the cooling unit 106 and the drawing unit 105 and close to the curtain of filaments f. The longitudinal slot-like outlet 133a extends in the transverse direction (perpendicular to the direction of fig. 6) substantially over the entire width of the curtain of filaments f for feeding the fibrous material MF substantially over the entire width of the curtain of filaments f.

In contrast to the supplying device 13 of fig. 1, the supplying device 13 'of fig. 6 does not comprise blowing means 134, but comprises a conveyor belt 135, which forms the lower wall of the feed channel 133' and is adapted to convey the fibrous material FM downwards to the outlet 133 a.

In operation, the fibrous material F is stacked in the duct 130. The conveyor belt 135 rotates continuously. The rollers 131, 132 rotate to continuously supply the fiber material MF to the conveying belt 135. The fibrous material MF is carried by the conveyor belt 135 and is continuously conveyed in the vicinity of the curtain of filaments f.

In the variant of fig. 6, a guide channel 106 delimited by a flap 107 and an air duct 108 extends between the outlet of the air-drawing unit 105 and the conveyor belt 11. Such a guide channel 106 is disclosed in US patent application US2008/0317895, the content of which is incorporated herein by reference. In operation, air is drawn from outside the guide channel 106 (arrow F7) and enters the guide channel 106 through the air duct 108 to equalize the air pressure inside the guide channel 106. The device of fig. 1 may also be equipped with such guide channels 106, fins 107 and air ducts 108.

In the variant of fig. 6, two consecutive textile apparatuses 1' are provided with the same conveyor belt 11. In another variant, the weaving device 1 'can be used alone or in combination with any other type of device suitable for laminating any type of layer (fabric layer or film) with the fibrous non-woven NW produced by the weaving device 1'.

Claims (86)

1. An apparatus for producing melt blown fibers (MF) and comprising: a die (104) having a plurality of spinning orifices; means (100, 101, 102, 103) for extruding at least one molten polymeric material through the spinning orifices of the die head (104) into the form of meltblown filaments (f); and means (104 a, 104 b) for blowing a hot primary gas flow (F1) towards the outlet of the die (104) to draw and attenuate the polymer filaments (F) at the outlet of the die; and a drawing unit (105) positioned below the die head (104) and adapted to generate an additional gas flow (F3) directed downstream for further drawing and attenuating the meltblown filaments (F).

2. The apparatus of claim 1, wherein the drawing unit (105) is adapted to break the meltblown filaments (f) into discontinuous Meltblown Fibers (MF).

3. The apparatus of claim 2, wherein the drawing unit (105) is adapted to break the meltblown filaments (f) into discontinuous Meltblown Fibers (MF) having an average length of more than 20mm, preferably more than 40mm, and preferably not more than 250 mm.

4. The apparatus according to any one of claims 1 to 3, wherein the drawing unit (105) comprises: a channel (1050) positioned below the die head (104) in such a way that the meltblown filaments (f) conveyed by the die head (104) can pass through the channel; and blowing means (1051-1055) adapted to blow said additional air flow (F3) into said channel (1050).

5. Apparatus according to claim 4, wherein said drawing unit (105) is adapted to generate a suction air flow (F4) above it, said suction air flow entering into said channel (1050).

6. The apparatus according to any one of the preceding claims, wherein the distance (d) between the outlet of the die head (104) and the inlet (1050 a) of the drawing unit (105) is adjustable.

7. The apparatus of any of the preceding claims, wherein all or part of the spinning orifices of the die head (104) are multilobal, and more particularly bilobal or trilobal.

8. The apparatus according to any of the preceding claims, further comprising an active surface (11) positioned below the drawing unit (105) and adapted to form a meltblown nonwoven web (MBW) from the Meltblown Fibers (MF) conveyed by the drawing unit (105).

9. The apparatus according to any of the preceding claims, further comprising a supply device (13) for continuously feeding a stream of Fibrous Material (FM) at a position between the die head (104) and the drawing unit (105) and close to the meltblown filaments (f).

10. The apparatus of any preceding claim, wherein the die head (104) is adapted to extrude vertical filaments and the additional gas flow (F3) is directed downwardly.

11. A method comprising the steps of:

(i) extruding at least one molten polymeric material through the spinning orifices of a die head (104) to form polymeric meltblown filaments (f),

(ii) drawing and attenuating the meltblown filaments at the outlet of the die head (104) with a primary stream of hot gas (F1),

(iii) a drawing unit (105) positioned below the die head (104) is used to generate an additional gas flow (F3) directed downstream to further draw and attenuate the meltblown filaments (F).

12. The method according to claim 11, wherein step (iii) is performed in such a way that the meltblown filaments (f) are broken into discontinuous Meltblown Fibers (MF).

13. The method of claim 12, wherein step (iii) is performed in such a way that the meltblown filaments (f) are broken into discontinuous meltblown fibers having an average length of more than 20mm, and preferably more than 40 mm.

14. The method according to claim 12 or 13, wherein step (iii) is performed in such a way that the meltblown filaments (f) are broken into discontinuous meltblown fibers having an average length of not more than 250mm, and preferably not more than 150 mm.

15. The process according to any one of claims 11 to 14, wherein step (iii) is performed in such a way that the meltblown filaments (f) are broken into discontinuous meltblown fibers having an average diameter of less than 10 μ ι η, and preferably less than 2 μ ι η.

16. The method of any one of claims 11 to 14, wherein step (iii) is performed in such a way that the meltblown filaments (f) are broken into discontinuous meltblown fibers having an average diameter between 10 and 400 μ ι η.

17. The method according to any of claims 11 to 16, wherein the Meltblown Fibers (MF) are transferred onto a moving surface (11 a) to form a meltblown nonwoven web (MWB).

18. The method according to any of claims 11 to 17, wherein the fibrous Material (MF) is continuously fed at a position between the die head (104) and the drawing unit (105) and close to the meltblown filaments (f).

19. The method according to any of claims 11-18, wherein the shape of the cross-section of the melt-blown fibers (MF) is non-circular.

20. The method according to any of claims 11-18, wherein the shape of the cross-section of the melt-blown fibers (MF) is multilobal, and preferably bilobal or trilobal.

21. The method of any one of claims 11-20, wherein the polymer has a melt index between 15 and 70.

22. The method according to any one of claims 10 to 21, wherein the wire is kept straight in the drawing unit and does not have any oscillation.

23. An apparatus for manufacturing a fibrous-containing nonwoven, the apparatus comprising: a die head (104, 104') having a plurality of spinning orifices; means for extruding at least one molten polymeric material through the spinning orifices of the die into the form of filaments (f); and a drawing unit (105) positioned below the die head and adapted to generate a gas flow (F3) directed downstream for drawing and attenuating the filaments (F), the apparatus further comprising: -supply means (13, 13 ') for continuously feeding a stream of Fibrous Material (FM) at a position between the die head (104, 104') and the drawing unit (105) and close to the filaments (f).

24. The apparatus of claim 23, wherein the die head does not comprise blowing means for blowing a hot primary gas flow (F1) towards the outlet of the die head (104).

25. Apparatus according to claim 23 or 24, further comprising cooling means (106) for blowing quenching air (F6) towards the filaments (F) at a position interposed between the die head (104 ') and the supply means (13').

26. The apparatus of claim 23, further comprising means (104 a, 104 b) for blowing a hot primary gas stream (F1) towards the outlet of the die head (104).

27. The apparatus according to any one of claims 23 to 26, wherein the drawing unit (105) is adapted to break the filaments (f) into discontinuous fibres (MF).

28. The apparatus of claim 27, wherein the drawing unit (105) is adapted to break the filaments (f) into discontinuous fibres (MF) having an average length of more than 20mm, preferably more than 40 mm.

29. Apparatus according to claim 27 or 28, wherein the drawing unit (105) is adapted to break the filaments (f) into discontinuous fibres (MF) having an average length not exceeding 250mm, and preferably not exceeding 150 mm.

30. The apparatus of any one of claims 23 to 29, wherein the drawing unit (105) comprises: a channel (1050) positioned below the die head (104, 104 ') in such a way that the filaments (f) conveyed by the die head (104, 104') can pass through the channel; and blowing means (1051-1055) adapted to blow said additional air flow (F3) into said channel (1050).

31. Apparatus according to claim 30, wherein said drawing unit (105) is adapted to generate a suction air flow (F4) above it, said suction air flow entering into said channel (1050).

32. The apparatus of any one of claims 23 to 31, wherein a distance (d) between the outlet of the die head (104, 104') and an inlet (1050 a) of the drawing unit (105) is adjustable.

33. The apparatus of any of claims 23 to 32, wherein all or part of the spinning orifices of the die head (104, 104') are non-circular orifices.

34. The apparatus of any of claims 23 to 32, wherein all or part of the spinning orifices of the die head (104, 104') are multilobal, and more particularly bilobal or trilobal.

35. The apparatus according to any one of claims 23 to 34, further comprising an active surface (11) positioned below the drawing unit (105) and adapted to form a nonwoven web from the fibers conveyed by the drawing unit (105).

36. The apparatus of any one of claims 23 to 35, wherein the die head (104) is adapted to extrude vertical filaments and the additional gas flow (F3) is directed downwardly.

37. A method for manufacturing a fibrous-containing nonwoven, wherein:

(i) extruding at least one molten polymer material through the spinning orifices of a die (104, 104') to form polymer filaments (f),

(ii) using a drawing unit (105) positioned below the die head (104, 104') to generate a gas flow (F3) directed downstream to draw and attenuate the filaments (F),

(iii) -continuously feeding a fibrous Material (MF) at a position between the die head (104, 104') and the drawing unit (105) and close to the filaments (f).

38. The method according to claim 37, wherein the filaments at the outlet of the die head (104) are drawn and attenuated by means of a hot primary gas flow (F1).

39. The method of claim 37, wherein the filaments are not drawn at the outlet of the die head (104).

40. The method according to claim 37 or 39, wherein the filaments are cooled down by a forced gas flow (F6) below the die head (104') before the feeding of the fibrous Material (MF).

41. The method according to any one of claims 37 to 40, wherein step (ii) is performed in such a way that the filaments (f) break into discontinuous fibres (MF).

42. A method according to any one of claims 37 to 40, wherein step (ii) is carried out in such a way that the filaments (f) break into discontinuous fibres having an average length of greater than 20mm, preferably greater than 40 mm.

43. A method according to any one of claims 37 to 42, wherein step (ii) is carried out in such a way that the filaments (f) break into discontinuous fibres having an average length of no more than 250mm, and preferably no more than 150 mm.

44. The method according to any one of claims 37 to 43, wherein step (ii) is carried out in such a way that the filaments (f) break into discontinuous fibres having an average diameter of less than 10 μm, and preferably less than 2 μm.

45. The method of any one of claims 37 to 43, wherein step (iii) is performed in such a way that the filaments (f) break into discontinuous fibres having an average diameter comprised between 10 and 400 μm.

46. A method according to any of claims 37 to 45, wherein the fibres (MF) are transferred onto a moving surface (11 a) to form a nonwoven web (MWB).

47. The method according to any of claims 37-46, wherein the shape of the cross-section of the fibers (MF) is non-circular.

48. Method according to any of claims 37-46, wherein the shape of the cross-section of the fibres (MF) is multilobal, and preferably bilobal or trilobal.

49. The method of any one of claims 37-48, wherein the polymer has a melt index between 15 and 70.

50. The method of any one of claims 37 to 49, wherein the wire is kept straight in the drawing unit and does not have any oscillation.

51. An apparatus for producing fibers (MF), and comprising: a die (104) having a plurality of spinning orifices; means (100, 101, 102, 103) for extruding at least one molten polymeric material through the spinning orifices of the die head (104) into the form of filaments (f); and a drawing unit (105) positioned below the die head (104) and adapted to generate a gas flow (F3) directed downstream for drawing and attenuating the filaments (F), and wherein the drawing unit (105) is adapted to break the filaments (F) into discontinuous fibres (MF).

52. The apparatus according to claim 51, wherein the drawing unit (105) is adapted to break the filaments (f) into discontinuous fibres (MF) having an average length of not more than 250mm, and preferably not more than 150 mm.

53. The apparatus of claim 51 or 52, wherein the drawing unit (105) is adapted to break the filaments (f) into discontinuous fibres (MF) having an average length of more than 20mm, preferably more than 40 mm.

54. Apparatus according to any one of claims 51 to 53, further comprising supply means (13) for continuously feeding a flow of Fibrous Material (FM) at a position interposed between said die head (104) and said drawing unit (105) and close to said filaments (f).

55. The apparatus of any one of claims 51 to 54, further comprising cooling means (106) for blowing quenching air (F6) towards the filaments (F) at a position interposed between the die head (104') and the drawing unit (105).

56. The apparatus of any one of claims 51 to 54, further comprising means (104 a, 104 b) for blowing a hot primary gas flow (F1) towards the outlet of the die head (104).

57. The apparatus of any one of claims 51 to 56, wherein the drawing unit (105) comprises: a channel (1050) positioned below the die head (104, 104 ') in such a way that the filaments (f) conveyed by the die head (104, 104') can pass through the channel; and blowing means (1051-1055) adapted to blow said additional air flow (F3) into said channel (1050).

58. Apparatus according to claim 57, wherein said drawing unit (105) is adapted to generate a suction air flow (F4) above it, said suction air flow entering into said channel (1050).

59. The apparatus of any one of claims 51 to 58, wherein a distance (d) between the outlet of the die head (104, 104') and an inlet (1050 a) of the drawing unit (105) is adjustable.

60. The apparatus of any one of claims 51 to 59, wherein all or part of the spinning orifices of the die head (104, 104') are non-circular orifices.

61. The apparatus of any of claims 51 to 59, wherein all or part of the spinning orifices of the die head (104, 104') are multilobal, and more particularly bilobal or trilobal.

62. The apparatus according to any one of claims 51 to 61, further comprising an active surface (11) positioned below the drawing unit (105) and adapted to form a nonwoven web from the fibers conveyed by the drawing unit (105).

63. The apparatus of any one of claims 51 to 62, wherein the die head is adapted to extrude vertical filaments and the additional gas flow (F3) is directed downwardly.

64. A process for producing a fiber (MF), wherein:

(i) extruding at least one molten polymer material through the spinning orifices of a die (104, 104') to form polymer filaments (f),

(ii) a drawing unit (105) positioned below the die head (104, 104') is used to generate a gas flow (F3) directed downstream in order to draw and attenuate the filaments (F) in such a way as to break them into discontinuous fibres (MF).

65. A method according to claim 64, wherein step (ii) is carried out in such a way that the filaments (f) break into discontinuous fibres having an average length of no more than 250mm, and preferably no more than 150 mm.

66. Method according to claim 64 or 65, wherein step (ii) is carried out in such a way that the filaments (f) break into discontinuous fibres having an average length of more than 20mm, preferably more than 40 mm.

67. The method of any one of claims 64 to 66, wherein step (ii) is performed in such a way that the filaments (f) break into discontinuous fibres having an average diameter of less than 10 μm, and preferably less than 2 μm.

68. The method of any one of claims 64 to 66, wherein step (iii) is performed in such a way that the filaments (f) break into discontinuous fibres having an average diameter of between 10 and 400 μm.

69. The method of any one of claims 64 to 68, wherein the filaments at the outlet of the die head (104) are drawn and attenuated by means of a hot primary gas flow (F1).

70. The method of any one of claims 64 to 68, wherein the filaments are cooled down by a forced air flow (F6) below the die head (104').

71. The method according to any of claims 64 to 70, wherein the fibrous Material (MF) is continuously fed at a position between the die head (104, 104') and the drawing unit (105) and close to the filaments (f).

72. The method according to any of claims 64 to 71, wherein the fibres (MF) are transferred onto a moving surface (11 a) to form a nonwoven web (MWB).

73. The method according to any of claims 64-72, wherein the shape of the cross-section of the fibers (MF) is non-circular.

74. The method according to any of claims 64-73, wherein the shape of the cross-section of the fibers (MF) is multilobal, and preferably bilobal or trilobal.

75. The method of any one of claims 64-74, wherein the polymer has a melt index between 15 and 70.

76. The method of any one of claims 64 to 75, wherein the wire remains straight and does not have any oscillation in the drawing unit.

77. A non-woven fabric comprising at least one layer (MBW) of non-staple fibres (MF) having a shaped cross-section and having an average length not exceeding 250mm, and preferably not exceeding 150 mm.

78. The non-textile fabric of claim 77, wherein the non-staple fibers are multi-lobal in cross-section.

79. The non-textile fabric of claim 77, wherein the non-staple fibers have a cross-sectional shape that is bi-lobal.

80. The non-textile fabric according to any one of claims 77 to 78, wherein the non-staple fibers (MF) have an average length of more than 20mm, and preferably more than 40 mm.

81. The non-textile fabric of any one of claims 77 to 80, wherein the non-staple fibers have an average diameter of less than 10 μm, and preferably less than 2 μm.

82. The non-textile fabric of any one of claims 77-81, wherein the non-staple fibers have an average diameter of between 10 μm and 400 μm.

83. The non-textile according to any one of claims 77 to 82, wherein the non-staple fibers (MF) are not crimped.

84. The non-textile fabric of any one of claims 77 to 83, wherein the non-staple fibers (MF) are meltblown fibers.

85. The non-woven fabric according to any one of claims 77 to 83, wherein the at least one layer (MBW) of non-staple fibers further comprises a Fibrous Material (FM) mixed with the non-staple fibers (MF).

86. Use of a non-woven according to any one of claims 77 to 85, or obtained from a method according to any one of claims 11 to 22, or obtained from a method according to any one of claims 37 to 50, or obtained from a method according to any one of claims 64 to 76, for the manufacture of absorbent products, and more particularly dry or wet wipes, diapers, training pants, sanitary napkins, incontinence products, mattresses.