Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H5/00—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length
  • D04H5/02—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length strengthened or consolidated by mechanical methods, e.g. needling
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H13/00—Other non-woven fabrics
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H5/00—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length

Definitions

• the present invention relates to a method for stabilizing the edges of a nonwoven web in accordance with the preamble of claim 1.
• the invention also relates to a device for implementing the method, as well as the nonwoven fabric obtained by using said method and apparatus.
• Nonwoven fabric production methods and plants which include at least one step of preparing a support web, formed by a long fiber layer or mat, at least one step of laying short staple fibers or wood pulp thereon and at least one step of bonding the short fibers together and to the preformed web on which they are laid, to provide the nonwoven fabric so obtained with the desired consistency.
• the preformed mat or web is composed of long fibers and may be obtained by carding operation, i.e. by using carding machines, or by continuous spinning, i.e. by using so called spinning machines.
• the wood pulp or the short fibers are generally conveyed and laid on the preformed long fiber web by the pneumatic action of machines that are known in the art as "airlaid machines”.
• Fiber bonding may be obtained by a thermal process, i.e. partial melting and welding at fiber contact points, or by a chemical process, i.e. partial melting and welding by means of a solvent, that is later evaporated, or yet by a mechanical process, i.e. weaving of fibers by using high pressure liquid jets.
• a thermal process i.e. partial melting and welding at fiber contact points
• a chemical process i.e. partial melting and welding by means of a solvent, that is later evaporated
• a mechanical process i.e. weaving of fibers by using high pressure liquid jets.
• water is used for the latter operation, which is generally known by those skilled in the art as "hydro-entangling".
• a long fiber web prepared by carding or spinning is overlaid first with a short fiber layer and then with another carded or spun long fiber web.
• the assembly is later bonded by a thermal treatment or by hydro- entangling.
• the short fiber layer is spread over an already bonded long fiber layer and is further bonded by another hydro-entangling operation.
• a further drawback lies in the presence of wood pulp at the web edges, which pulp has to be removed before bonding, for instance by local suction. Such suction is not easily controlled, as the long fibers of the preformed web or mat also tend to be sucked in.
• Such fibers tend to clog and soil the short fiber conveying and laying system, whereto the sucked fibers are fed, and this negatively affects proper operation of such system.
• the wood pulp at the edge of the web causes faster soiling of the hydro- entangling machine, and consequent defects in the finished product, as well as the need for more frequent cleaning and maintenance operations on the machine.
• a general object of this invention is to obviate the above drawbacks by providing a method for manufacturing nonwoven fabric, which allows to obtain a uniform nonwoven fabric, as described before, in a reliable and cost-effective manner, even at high feed and production speeds.
• a further object is to conceive a short fiber laying method which reduces nonwoven fabric defects especially at the edges thereof.
• Yet another object is to provide a short fiber laying method which allows to easily adjust suction of excess short fibers laid at the web edges.
• Another object is to provide a short fiber laying method, which allows to recover the short fibers or wood pulp that have been sucked in, with no presence of long fibers from the preformed mat or web.
• a further object is to provide a nonwoven fabric producing method which can operate continuously and with a high productivity.
• a method for stabilizing the edges of a nonwoven web wherein the fabric is obtained by carding or continuously spinning long fibers and laying them over a movable support surface, having a predetermined advancement speed to form a web with substantially straight side edges, subsequently laying a short fiber layer on said web, bonding said short fiber layer with said web to form the nonwoven fabric, characterized in that, before laying the short fibers the side edges of the web are at least partly shielded and compressed against the movable support surface.
• an edge stabilizing device for a nonwoven web for implementation of the above method, suitable to be mounted on a short fiber laying unit placed downstream of a continuous long fiber web spinning station, which web is fed over a movable support surface, which device, according to claim 9, is characterized in that it comprises means for shielding and compressing the longitudinal edges of the web in the short fiber laying area, so as to prevent them from being laid along said edges and to increase the web stability, thus avoiding any curl or fold thereon.
• the device of the invention allows to prevent wood pulp or short fibers from being laid on the web edges, thereby obviating the drawbacks of pollution and of wood pulp and short fiber accumulation on the downstream machine for mechanically bonding the web by high pressure water jets.
• FIG. 1 shows a flowchart of the inventive method
• Fig. 2 is a side schematic view of a device for implementing the inventive method
• Fig. 3 is a front schematic view of the device of Fig. 2;
• Fig. 4 is a top schematic view of the device of Fig. 2;
• Fig. 4a is a sectional view of an isolated and enlarged detail of Fig. 4, as taken along an axis IV-IV;
• Fig. 5 is a side schematic view of the detail of the device for implementing the inventive method
• Fig. 6 is a front schematic view of the device of Fig. 5.
• a process for making a nonwoven fabric T generally comprises step A in which long fibers F
• step D in which a layer of short fibers F c , possibly including wood pulp, is laid over web V.
• step E is executed in which the short fibers F c are bonded with the long fibers F ⁇ of the web V to form the nonwoven fabric T.
• short fibers F c may be laid by using air, according to a process known per se by those skilled in the art as "airlaid process", whereas the bonding step E may be performed by using high pressure jets of water according to the hydro- entangling technique.
• which form the carded web V may be laid over a movable support surface, for instance a belt conveyor which is drive at a predetermined speed S.
• step D of laying the short fiber F c the longitudinal edges B, B' of the web V are subjected to step C in which the long fibers F
• the shielding and compressing action C is exerted on the longitudinal edges B, B' of the web over a length that corresponds at least to the short fiber laying area, and over a predetermined transverse width W.
• edges of the web V were experimentally found to be properly stabilized with a width W of the shielding and compression regions ranging from 10 to 100 mm.
• the compression exerted on the edges B, B' may be adjusted according to typology of web W, in such a manner as to allow a free feed thereof.
• the excess short fibers F c on the conveyor are sucked, upon laying thereof on the web at a predetermined distance from the edges B, B', outside the edge covering and compression area, to prevent long fibers F ⁇ of web V from being sucked along, and conveyed back to the fiber laying unit.
• a device 1 for carding or spinning and laying long fibers F ⁇ to form a web V is placed upstream of a unit 2 which lays short fibers F c by using air, to prepare a nonwoven fabric T.
• Device 1 for treating long fibers F ⁇ comprises a carding or spinning unit (not shown) and a unit for laying long fibers F ⁇ on a movable support surface.
• the latter is, for example, a conveyor belt 3 extending between end rollers 4, 5.
• the short fiber F c laying unit 2 is placed downstream of the device 1 and may use the same conveyor belt 3.
• the laying device 2 comprises means for shielding and compressing the longitudinal edges of the web, overall designated as 6, 6', located in the short fiber F c laying area, to prevent short fibers from being laid along the edges B, B' and to increase the stability of the web V, thus avoiding any curling or folding thereof in these areas.
• the shielding and compressing means 6, 6' are arranged over belt 3 along the short fiber laying unit 2 to shield and compress the edges of said web against the surface of belt 3.
• the shielding and compressing means 6, 6' are removably secured to the short fiber laying unit 2 by appropriate connection means 7, which may be adjusted at a variable transverse distance to fit the width of the web V.
• connection means 7 include adjustment means 8, 9 to control the pressure over said edges.
• the shielding and compressing means 6, 6' comprise a pair of longitudinal plates 10, 10' having curved end portions 11 , 12, 11', 12' which define torsion springs secured to the adjustment means 8, 9.
• Adjustment means 8, 9 may include pins 14, 14', 15, 15' for the torsion of the end portions 11 , 12, 11 ', 12' of plates sheets 10, 10'.
• Pins 14, 14', 15, 15' may be rotated from the outside by any means, not shown, to impart bending moments acting on substantially vertical planes to the end portions 11 , 12, 11', 12' of the plates 10, 10'.
• plates 10, 10' are made of an elastic metallic material, particularly steel, or of a reinforced or composite plastic material.
• the device also includes means 16, 16' for suction of excess short fibers laid on the movable support surface, which suction means may consist of intakes 16 located at the opposite sides of the movable support surface 3, outside the edge B, B' covering and compression area.
• Suction means 16, 16' may be connected by suitable pipes, not shown in the drawings, to the short fiber laying unit 2 to recirculate in this area the exceeding pulp or short fibers F c .
• plates 10, 10' have such a width as to cover the edges B, B' by a minimum transverse width W of 10 to 100 mm, thereby preventing short fibers from being laid thereon.
• the sheets have a transverse width (H) of more than at least 10 mm.
• H transverse width
• the machine for making the nonwoven fabric T with stabilized edges comprises a continuous long fiber web spinning station 1 , followed by a short fiber laying unit 2 comprising a web edge stabilization device.
• This provides an increased web stability, prevents wrinkles and folds at the edges and counters any motion generated by the turbulence which is caused by the airlaid unit.
• the nonwoven fabric T with stabilized edges which is obtained by a device as described above comprises a web V of carded or spun long fibers F ⁇ , which is overlaid with a layer of short fibers F c , interwoven with the long fibers of the web V, whose edges B, B' are cleared of short fibers F c , and are continuos, straight, have no folds and curls and no processing scraps.
• nonwoven fabric edge stabilizing method and device according to the invention allow to achieve the intended objects and particularly to obtain a uniform nonwoven fabric in a cost-effective and reliable manner, even at high feed speeds and high production rates, thereby minimizing the defects of the final product, especially at the edges thereof.
• this method and device allow to prevent short fibers from being laid at the web edges, and to avoid clogging of the units for recycling them.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Preliminary Treatment Of Fibers (AREA)
• Treatment Of Fiber Materials (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=32051261

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (1)

Family Cites Families (5)

• 2002
  • 2002-10-01 IT IT000209A patent/ITVI20020209A1/it unknown
• 2003
  • 2003-10-01 DE DE60304367T patent/DE60304367T2/de not_active Expired - Fee Related
  • 2003-10-01 AU AU2003265072A patent/AU2003265072A1/en not_active Abandoned
  • 2003-10-01 ES ES03799046T patent/ES2262025T3/es not_active Expired - Lifetime
  • 2003-10-01 WO PCT/IB2003/004343 patent/WO2004031463A2/en not_active Ceased
  • 2003-10-01 EP EP03799046A patent/EP1556536B1/de not_active Expired - Lifetime
  • 2003-10-01 AT AT03799046T patent/ATE321906T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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