Apparatus for spinning fibres and producing a fibrous-containing nonwoven
09617658 ยท 2017-04-11
Assignee
Inventors
Cpc classification
D01D5/088
TEXTILES; PAPER
D04H1/56
TEXTILES; PAPER
Y10T442/609
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
D01D5/14
TEXTILES; PAPER
D01D5/253
TEXTILES; PAPER
Y10T442/611
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T442/608
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
D01D5/253
TEXTILES; PAPER
D01D5/14
TEXTILES; PAPER
D04H1/56
TEXTILES; PAPER
D01D5/088
TEXTILES; PAPER
Abstract
The apparatus (1) is used for producing melt-blown 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).
Claims
1. An apparatus for making a fibrous-containing nonwoven comprising: a die head with several spinning orifices: means for extruding at least one melted polymeric material through the spinning orifices of the die head in the form of filaments; a drawing unit positioned below the die head, and adapted to create a gas flow that is oriented downstream for drawing and attenuating the filaments; and supplying means for continuously feeding a stream of fibrous material at a position between the die head and the drawing unit, and nearby the filaments.
2. The apparatus of claim 1, wherein the drawing unit is adapted to break the filaments into discontinuous fibres.
3. The apparatus of claim 2, wherein the drawing unit is adapted to break the filaments into discontinuous fibres having an average length higher than 20 mm and not more than 250 mm.
4. The apparatus of claim 3, wherein the drawing unit is adapted to break the filaments into discontinuous fibres having an average length greater than 40 mm and not more than 150 mm.
5. The apparatus of claim 1, wherein the drawing unit comprises a channel that is positioned below the die head, in such a way that the filaments delivered by the die head can pass through the channel, and air blowing means adapted to blow the gas flow inside the channel.
6. The apparatus of claim 5, wherein the drawing unit is adapted to create above the drawing unit a sucked air flow that enters into the channel.
7. The apparatus of claim 1, wherein the distance between the outlet of the die head and the inlet of the drawing unit is adjustable.
8. The apparatus of claim 1, wherein whole or part of the spinning orifices of the die head are non circular orifices.
9. The apparatus of claim 1, wherein whole or part of the spinning orifices of the die head are multilobal.
10. The apparatus of claim 1, further comprising a movable surface positioned below the drawing unit.
11. The apparatus of claim 1 wherein the die head is adapted to extrude vertical filaments, and the gas flow is oriented downwardly.
12. The apparatus of claim 1, further comprising cooling means for blowing a quenching air towards the filaments at a position between the die head and the drawing unit.
13. The apparatus of claim 1, wherein the die head does not comprise blowing means for blowing a hot primary gas flow towards the outlet of the die head.
14. The apparatus of claim 1, further comprising means for blowing a hot primary gas flow towards the outlet of the die head in order to form meltblown filaments.
15. The apparatus of claim 1, further comprising a thermal bonding unit for thermo-bonding the fibrous-containing nonwoven.
16. The apparatus of claim 1, wherein the supplying means includes a conveyor belt for continuously delivering the fibrous material.
17. The apparatus of claim 9, wherein all or part of the spinning orifice of the die head is bilobal.
18. The apparatus of claim 9, wherein all or part of the spinning orifice of the die head is trilobal.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Other characteristics and advantages of the invention will appear more clearly on reading the following description of preferred embodiments of the invention, which description is given by way of non-limiting example and is made with reference to the accompanying drawings, in which:
(2)
(3)
(4)
(5)
(6)
(7)
DETAILED DESCRIPTION
(8) In reference to
(9) As already known in the art, the meltblow equipment 10 comprises: an extruder 100, a hopper 101 containing polymeric pellets P, said hopper 101 being connected to the extruder 100 and being adapted to supply by gravity the extruder 100 with polymeric pellets P, a spinning pump 102 connected to the outlet of the extruder via a duct 103, a meltblow die head 104 that knowingly comprises one or several parallel rows of spinning orifices that extend in the cross direction (direction perpendicular to
(10) These components 100 to 104 of the meltblow equipment 10 are already known in the art and will not be described in details.
(11) In operation of the meltblow equipment 10, the polymeric pellets P are melted by the extruder 100 into a molten polymeric material, which is fed by the extruder 100 to the spinning pump 102. Said spinning pump 102 feeds the die head 104 in order to extrude the molten polymeric material through the spinning orifices of the die head 104, and to form at the outlet of the die head 104 a vertical curtain of polymeric meltblown filaments f. This vertical curtain of polymeric meltblown filaments f extends in the cross direction perpendicular to the plane of
(12) The hot primary air (heated air flows F1) is drawing and attenuating the meltblown filaments f immediately at the outlet of the die head 104, while the polymer is still in the molten state. This hot primary air F1 is typically heated at a temperature which is substantially equal or slightly higher than the melt temperature of the polymer. At the outlet of the die head, a large volume of cooling air (air flows F2), hereafter called secondary air is drawn into the primary air. This secondary air F2 is cooling down the polymeric filaments f downstream from the die head 104 and provides the quenching of the polymeric meltblown filaments f.
(13) The meltblow equipment 10 newly comprises an additional air-drawing unit 105 that is positioned below the die head 104, and that is 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.
(14)
(15) In reference to the particular embodiment of
(16) In operation, the blowing duct 1055a is supplied with gas under pressure at ambient temperature, and more particularly with air under pressure at ambient temperature. This air is exhausted in chamber 1051 through the slot-type outlet 1055a, and then passes successively in the chambers 1052, 1053 and 1054. This air under pressure is exhausted in the channel 1050, through the slot-type outlet 1054a, in the form of downward air flows F3 of high velocity. Each slot-type outlet 1054a is inclined in such a way that the air flows F3 are oriented downstream and substantially in the longitudinal direction of the filaments f, i.e. substantially in the same longitudinal downstream direction as the flow of polymer forming the filaments f.
(17) In operation, the polymeric meltblown filaments f are passing through the channel 1050 of the drawing unit 105 and are drawn and attenuated by the air flows F3 (
(18) The high velocity air flows F3 also create by Venturi effect an air suction above the drawing unit 105. This air suction creates additional air flows F4 that are sucked into the channel 1050 through the inlet 1050a, and that contribute to the cooling and solidification of the filaments f.
(19) In the drawing unit 105, the airflows do not create turbulences that would impart a flapping movement or that would create undulations in the filaments. In the drawing unit 105, the filaments remain straight and do no have any flapping movement.
(20) The velocities of the air flows F1 (died head 104) and F3 (drawing unit 105) can be advantageously selected in such a way to break the filaments f at the outlet 1050b of the drawing unit 105 and to form discontinuous meltblown fibres MF having a predetermined average length (
(21) The velocities of the air flows F1 and F3 can be advantageously adjusted separately, which improves the flexibility of the setting of the meltblow equipment 10.
(22) More particularly, in the invention the distance between the drawing unit 105 and the outlet of the die head 104 can be adjusted in order to break the filaments f and form discontinuous non-staple fibres of specific average length. Preferably, the distance between the drawing unit 105 and the outlet of the die head 104 can be adjusted in order to break the filaments f and form discontinuous non-staple fibres having an average length of not less than 20 mm, preferably higher than 40 mm, and of not more than 250 mm, and preferably of not more than 150 mm.
(23) Thanks to the use of this additional drawing unit 105, the stretching of the polymer chains of the filaments f can be greater than the usual stretching practised in a standard meltblow equipment, which advantageously enables to increase the tenacity of the meltblown fibres MF, and thereby the tenacity and MD (Machine Direction) tensile strength of the meltblown nonwoven web MBW comprising such fibres.
(24) In the invention, the air drawing unit 105 can be used and adjusted in order to produce very fine denier fibres MF having an average diameter less than 10 m, and preferably less than 2 m, but can also be advantageously used and adjusted in order to produce thicker discontinuous non-staple fibres MF having an average diameter of not less than 10 m, and preferably between 10 m and 400 m.
(25) In another variant of the invention, the velocities of the air flows F1 (died head 104) and F3 (drawing unit 105) can also be advantageously selected in such a way that the filaments f of the drawing unit 105 are not broken at the outlet 1050b and thus form continuous meltblown fibres MF.
(26) Thanks to the use of the air drawing unit 105, the polymer(s) used for making the filaments can advantageously have a low melt flow index, and in particular a melt flow index between 15 and 70 (ASTM D1238). It is thus possible to spin shaped fibres having a non-circular cross section, but having form example a multilobal cross section, in particular a bilobal cross section.
(27) In the embodiment of
(28) The terms fibrous material used therein and in the claims encompass any material comprising short length fibres and/or comprising particles.
(29) The average length of the fibres of the fibrous material FM will generally not exceed the average length of the meltblown fibres MF. But fibres for the fibrous material, having an average length that is greater than the length of the meltblow fibres MF can be however also used.
(30) More particularly, the fibrous material can advantageously comprise pulp.
(31) The term pulp as used therein and in the claims refers to absorbent material made of or containing fibres from natural sources such a as woody and non-woody plants. Woody plants (i.e. wood-pulp) include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute hemp, and bagasse. Typically, the average length of the pulp fibres is not more than 5 mm. Longer fibres can be however also used for the fibrous material FM.
(32) Within the scope of the invention, the fibrous material can be made solely of pulp, or can also be made of a dry mixture of pulp with other materials (fibres and/or particles). In particular the fibrous material can comprise dry mixture of pulp and particles of superabsorbent material (SAM).
(33) The fibrous material can also comprise staple fibres (natural and/or synthetic), and for example cotton fibres.
(34) In the particular embodiment of
(35) The supplying means 13 also comprise blowing means 134 that comprise a longitudinal slot-type outlet 134a extending in the cross-machine direction on substantial the whole width of the chimney. The blowing means 134 are adapted to blow compressed air through the said outlet 134a.
(36) The supplying means 13 also comprise a feeding nozzle 133, that is positioned below the feeding roll 132. This nozzle 133 has an outlet 133a for the fibrous material MF. Said outlet 133a forms a longitudinal slot and is positioned between the die head 104 and the drawing unit 105, and nearby the curtain of meltblown filaments f. This longitudinal slot-type outlet 133a extends in the cross-direction direction (direction perpendicular to the
(37) In operation, the fibrous material F is stacked in the chimney 130 Compressed air is continuously exhausted by the blowing means 134, through the longitudinal slot-type outlet 134a, inside the nozzle 133 (air stream F5). The rolls 131,132 are rotated in order to continuously feed the nozzle 133 with fibrous material MF. Said fibrous material MF is entrained by the air stream 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 delivered nearby to the curtain of meltblown filaments f.
(38) Thanks to the use of the air-drawing unit 105, the fibrous material MF enters in contact with the meltblown filaments f and is entrained in the drawing unit 105. In addition, thanks to the air flows F4 (
(39) At the outlet 1050b of the drawing unit 105, the fibrous material FM is advantageously intimately mixed and also partially heat bonded with the meltblown fibres MF. As a result, a fibrous-containing meltblown web MBW is formed onto the surface 11a of the conveyor belt 11, wherein the intermingling and bonding of the fibrous material MF with the meltblown fibres MF are improved in comparison for example with the technical solution disclosed in U.S. Pat. No. 4,931,355 and in U.S. Pat. No. 4,939,016 to Radwanski et al. As a result, the loss of fibrous material FM is dramatically reduced when the fibrous-containing meltblown web MBW is subsequently consolidated and/or handled.
(40) In the invention, the use of the additional drawing unit 105 also enables to practice air flows F1 and F2 of lower velocities compared to a standard meltblow equipment having only a meltblown die head without additional drawing unit 105, like for example the meltblow equipment disclosed in U.S. Pat. No. 4,931,355 and in U.S. Pat. No. 4,939,016 to Radwanski et al. By reducing the velocity of the air flows F1 and F2, there is advantageously less risk that the fibrous material FM is being pushed back. As a result, it is advantageously easier to incorporate higher amount of fibrous material inside the meltblown fibres MF.
(41) In the particular embodiment of
(42) In operation, the conveyor belt 11 is used for transporting and passing the fibrous-containing meltblown nonwoven web MBW between the two rolls 14a, 14b in order to pre-consolidate the fibrous-containing meltblown nonwoven web by heat and mechanical compression (thermo-bonding).
(43) The invention is not limited however to the use of thermal bonding unit for consolidating the fibrous-containing meltblown nonwoven web MBW, but any other consolidating technique already known in the art can be used, such as for example mechanical bonding, hydroentangling, ultrasonic bonding, air-through bonding, and adhesive bonding.
(44) The hot primary air F1 can be generally obtained like in a standard meltblown process by heating the air with a heat source positioned outside the die head 104. But in another variant of the invention, the heated air can be heated only by the heat generated by the die head 104, when this air passes trough the die head 104.
(45) In another variant of the invention, the apparatus of
(46) In another variant of the invention, the primary air F1 can be generated at low speed in such a way that this primary air is not necessarily used for drawing an attenuating the filaments f at the outlet of the die head 104, but in such a way only to clean the die head 104 and avoid that broken filaments spoil the spinning orifices.
(47) In another variant of the invention, the apparatus of
(48) The polymer(s) P used for making the fibres MF can be any melt spinnable polymer(s) than can be extruded through a die head. Good candidates are for example polyolefin (in particular homo or copolymer of polypropylene or polyethylene), homo or copolymer of polyester, or homo or copolymer of polyamide or any blend thereof. It can be also advantageously any biodegradable thermoplastic polymer, like for example homo or copolymer of polylactic acid (PLA), or any biodegradable blend comprising a homo or copolymer of PLA. In such a case, when the fibrous material is made of biodegradable material, the nonwoven web MBW is advantageously totally biodegradable.
(49) The fibres MF will be generally non elastic. But elastomeric or elastic fibres MF can be however also used.
(50) The fibres MF can be monocomponent or multicomponent fibres, especially bicomponent fibres, and more especially sheath/core bicomponent fibres. When bicomponent fibres are produced, two extruders are used for feeding simultaneously the die head 104 with each polymer.
(51) Various shapes in cross section for the fibres MF can also be practised (round shape, oval shape, multilobal shape, in particular bilobal shape, trilobal shape, etc. . . . ). The shape in cross section of the meltblown fibres MF is determined by the geometry of the spinning orifices of the die head 104.
(52) The bonding of the fibrous material FM with the fibres is however surprisingly improved when multilobal-shaped fibres MF are used, especially when bilobal fibres like the one shown in
(53)
(54) In particular, this production line 2 comprises (
(55) Upstream from these supplying means 20, the production line 2 comprises successively four apparatus 22, 23 (
(56) The first apparatus 22 is used for continuously spinning the first meltblown web MBW1 directly onto the spunbonded nonwoven web S. The second apparatus 23 is used for continuously spinning the second intermediate fibrous-containing meltblown web MBW2 directly onto the first meltblown web MBW1. The third apparatus 24 is used for continuously spinning the third fibrous-containing meltblown web MBW3 directly onto the second intermediate fibrous-containing meltblown web MBW2. The fourth apparatus 25 is used for continuously spinning the fibrous-containing meltblown web MBW4 directly onto the third intermediate fibrous-containing meltblown web MBW3
(57) The laminate MBW4/MBW3/MBW2/MBW1/S is then subsequently transported to a standard thermal bonding unit 26, in order to heat bond the different layers of the laminate and obtain a consolidated laminate. The consolidated laminate MBW4/MBW3/MBW2/MBW1/S is then knowingly wounded in line around a storage roll 27a.
(58) In a preferred embodiment, the meltblown fibres of the first and fourth meltblown nonwoven web MBW1 and MBW4 are bilobal or trilobal and the meltblown fibres of the second and third meltblown nonwoven web MBW2 and MBW3 can have any shape, and in particular can be round. The invention is however not limited to such a particular laminate.
(59) More generally, within the scope of the invention a laminate comprising at least one fibrous-containing meltblown web of the invention, laminated with one or more other layers, including notably spunbonded layer, carded layer, meltblown layer, plastic film, can advantageously be produced.
(60) The fibrous-containing meltblown web of the invention or a laminate comprising at least one fibrous-containing meltblown web of the invention can be used advantageously for making absorbent products, and more particularly dry wipes, or wet wipes, or diapers, or training pants, or sanitary napkins, or incontinence products, or bed pads.
(61)
(62) In this variant, the died head 104 of the spinning apparatus 1 is modified in order to extrude several rows (three rows in this particular example) of polymeric filaments f, instead of one row for the apparatus of
(63) A cooling unit 106 is mounted below the outlet of the die head. Said cooling unit 106 comprises two blowing boxes 106a positioned on each side of the filaments f and adapted to blow several transverse forced air flows F6 towards the filaments f, in order to cool down and quench the filaments f, in a way similar to the quenching air used in a standard spunbonding apparatus. This quenching air F6 is for example at a temperature between 5 C. and 20 C.
(64) The same drawing unit 105 as the one previously described is being used at a position below the cooling unit 106 for generating the same air flows F3 oriented downstream as the ones previously described, said air flows F3 drawing and attenuating the filaments f.
(65) All the previous explanations made before in connection with the drawing unit 105 of the first embodiment of
(66) In the particular embodiment of
(67) The supplying means 13 also comprise a feeding channel 133 that is positioned below the feeding roll 132. This feeding channel 133 has an outlet 133a for the fibrous material MF. Said outlet 133a forms a longitudinal slot and is positioned between the cooling unit 106 and the drawing unit 105, and nearby the curtains of filaments f. This longitudinal slot-type outlet 133a extends in the cross-direction direction (direction perpendicular to the
(68) In contrast with the supplying means 13 of
(69) In operation, the fibrous material F is stacked in the chimney 130. The conveyor belt 135 is continuously rotated. The rolls 131,132 are rotated in order to continuously feed the conveyor belt 135 with fibrous material MF. Said fibrous material MF is entrained by the conveyor belt 135 and is continuously delivered nearby to the curtains of filaments f.
(70) In the variant of
(71) In the variant of