Apparatus for making melt-blown multilayer nonwoven

Abstract

An apparatus for making nonwoven has a mesh belt moving in a horizontal direction and upstream and downstream spinnerets spaced apart in the direction above the belt and having downwardly opening tips at respective vertical spacings above the belt and each emitting fibers that are deposited at locations on the belt directly below the spinnerets to form thereon respective nonwoven layers. A support carrying the belt can be moved vertically and pivoted to orient the belt into a position forming an acute angle with respect to horizontal and thereby vary the spacings.

Claims

1. An apparatus for making nonwoven, the apparatus comprising: a mesh-belt system having an upstream endless section and a downstream endless section aligned therewith in a horizontal direction; respective upstream and downstream spinnerets spaced apart in the direction above the upstream and downstream sections of the mesh-belt system, having downwardly opening tips at respective vertical spacings above the respective sections of the mesh-belt system, and each emitting fibers that are deposited at locations on the respective sections of the mesh-belt system directly below the spinnerets to form on the respective sections respective nonwoven layers; a support carrying the mesh-belt system; means for moving the support and thereby orienting the mesh-belt system into a position forming an acute angle with respect to horizontal and thereby varying the spacings; and upstream and downstream drive means respectively connected to the upstream and downstream sections for independently moving same in or against the direction.

2. The apparatus according to claim 1, wherein the support is pivotal about a horizontal axis.

3. The apparatus according to claim 2, wherein the means for moving the support lifts and/or pivots the support.

4. The apparatus according to claim 3, wherein the axis extends transversely to the direction.

5. The apparatus according to claim 4, wherein the axis is, relative to a longitudinal extension of the mesh-belt system, in a middle third of the mesh-belt system.

6. The apparatus according to claim 5, wherein the angle is +/−10° relative to horizontal.

7. The apparatus according to claim 3, wherein the means for moving the support can lift an upstream or downstream end of the mesh-belt system from a level horizontal position of the mesh-belt system by 100 to 500 mm.

8. An apparatus for making nonwoven, the apparatus comprising: a mesh-belt system having an upstream endless section and a downstream endless section aligned therewith in a horizontal direction; respective upstream and downstream spinnerets spaced apart in the direction above the upstream and downstream sections of the mesh-belt system, having downwardly opening tips at respective vertical spacings above the respective sections of the mesh-belt system, and each emitting fibers that are deposited at respective locations on the mesh-belt system directly below the spinnerets to form on the respective sections respective nonwoven layers; a support carrying the mesh-belt system; means for moving the support and thereby orienting the mesh-belt system into a position forming an acute angle with respect to horizontal and thereby varying the spacings; and guide means for moving one of the layers under the endless section on which the other layer is deposited.

9. An apparatus for making a multilayer nonwoven, the apparatus comprising: a base; a support carried by the base; an endless belt system supported on and movable with the support and having an upper reach extending generally horizontally; a drive for advancing the belt system such that the upper reach moves in a machine direction; upstream and downstream spinnerets fixed above the base, separated in the direction by a gap, having downwardly open tips spaced apart in the direction at vertically fixed positions at respective spacings above respective deposition locations on the belt system, and emitting melt-blown fibers that drop from the tips onto the respective deposition locations to form respective layers; a pivot supporting the support and belt system on the base for pivoting about a horizontal axis transverse to the direction; a guide on the base only allowing the pivot to move vertically; and actuators for raising and lowering the pivot on the base and for pivoting the support on the base about the axis to vary the spacings.

10. The apparatus according to claim 9, wherein the belt system has an upstream endless section and a downstream endless section under the respective upstream and downstream spinnerets and separated by a gap, the drive including an upstream and downstream drive each capable of rotating the respective section such that it moves in or against the direction.

11. A method of operating the apparatus of claim 10, the method comprising the steps of: in a first operating mode, driving the upper reaches of both sections in the same direction and thereby passing fibers deposited on the upstream section across the gap to the downstream section where the downstream spinneret deposits fibers on the fibers from the upstream section; in a second operating mode, driving the upper reaches of both sections in the same direction while guiding the fibers while deflecting the fibers from the upstream section down into the gap and under the downstream section, and thereafter uniting the fibers from the upstream section with the fibers from the downstream section at a downstream end of the upper reach of the downstream section; and in a third operating mode, driving the upper reaches of the sections oppositely in respective directions away from the gap and deflecting the fibers down from an upstream end of the upstream reach and then under both of the sections, and thereafter uniting the fibers from the upstream section with the fibers from the downstream section at a downstream end of the upper reach of the downstream section.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a schematic side view of a first embodiment of an apparatus for making nonwoven according to the invention with a first mesh-belt system according to the invention;

(3) FIG. 2 is a perspective view of a second mesh-belt system according to the invention;

(4) FIG. 3 is a schematic side view according to the invention of a second embodiment of an apparatus for making nonwoven in a first mode of operation;

(5) FIG. 4 shows the apparatus for making nonwoven of FIG. 3 in a second operating mode;

(6) FIG. 5 shows the apparatus for making nonwoven from FIG. 3 in a third operating mode; and

(7) FIG. 6 shows the apparatus for making nonwoven of FIG. 3 in a fourth operating mode.

SPECIFIC DESCRIPTION OF THE INVENTION

(8) As seen in FIG. 1 an apparatus for making nonwoven according to the invention has two melt-blowing spinnerets 1 and 2. Below the melt-blowing spinnerets 1 and 2 there is a mesh-belt system 5 with a single endless circulating mesh belt 6. The rotating mesh belt 6 here is guided over eight rollers 20 and is driven by a motor 15 so that its upper reach moves in a direction D. The upper reach of the mesh belt 6 faces the melt-blowing spinnerets 1 and 2 face. A lower reach of the belt of the system 5 runs opposite to this transport direction D.

(9) First and second air ducts 18 and 19 open upward between the upper and lower reaches of the mesh belt 6, respectively below the first and second spinnerets 1 and 2. The air ducts 18 and 19 can be connected to a common blower or each have their own blower such as shown schematically at 28. Air moves downward in the ducts 18 and 19 so as to be sucked in from above the mesh belt 6 and pass through holes in the mesh belt 6 into the air ducts 18 and 19. The air ducts 18 and 19 are directly below the respective deposition location or the respective melt-blowing spinnerets 1 and 2.

(10) Fibers 3 of the first melt-blowing spinneret 1 initially form their own first nonwoven web layer 12. As soon as this layer 12 reaches the deposition location of the second fibers 4, these second fibers 4 form a second nonwoven web layer 13 on top of the first layer 12. The second nonwoven web layer 13 deposited on the first layer 12 forms therewith a multilayer nonwoven 14. After leaving the mesh belt 5, the multilayer nonwoven 14 is passes over a guide roller 21 and to a consolidater 17. The consolidater 17 of this embodiment can be a calender whose rollers compress and heat the multilayer nonwoven 14 to form it into a laminate. Due to deposition of the hot second fibers 4 directly on the first fibers 3 in this embodiment, a first lamination bonding already takes place on deposition, which is why the consolidater 17, in particular, a thermal consolidater 17 is not required for all nonwoven products.

(11) FIG. 1 shows how the two melt-blowing spinnerets 1 and 2 here have respective nozzle tips 8 and 9. The nozzle tip 8 opens at a vertical spacing A1 above the surface of the mesh belt 6, and the nozzle tip 9 similarly is set at a vertical spacing A2 above the surface of the mesh belt 6. The spacings A1 and A2 are set individually and independently of each other in accordance with the type of resin being melt blown, the amount of air cooling desired, and other production factors.

(12) For this reason, the mesh belt 5 according to FIG. 2 has a pivot axis 10 as well as actuators 27 that can pivot the entire mesh-belt system 5 about this axis to a maximum angle α. Due to the use of two separate actuators 27, not only can the set angle α be adjusted, but vertical adjustment through a stroke Δz is also possible. The two degrees of freedom α and Δz make it possible, within a certain framework, to change the spacings A1 and A2 wholly independently of each other.

(13) The actuators 27 may be electromechanical or hydraulic cylinders, for example. They preferably have upper ends connected to side walls 24 forming the support of the mesh-belt system 5. Lower ends of the actuators 27 are preferably mounted on a base formed by a carriage 23 mounted on rails 22. The carriage 23 on the rails 22 permit rapid maintenance of the melt-blowing spinnerets 1 and 2 from below by making it easy to move the entire belt system 5 out of the way from underneath the spinnerets 1 and 2.

(14) The pivot axis 10 of this embodiment may be formed by an axle with roller ends seated in vertical guide slots 26 in upright plates 26 carried on the base 23 and flanking the belt system 5. The opposite and not shown side of the mesh belt 5 is identical or symmetrical to the side shown in FIG. 2. The axle 10 supports the belt system 5 so that it cannot move in the horizontal machine direction D.

(15) The two vertical guide slots 26 in the base plates 25 thus only allow vertical movement, as indicated at a slightly lower set pivot axis 10′ in the slots 26. In addition, the pivot guide plates 25 permit rotation, as shown by the position angle α. The four actuators 27, two on each side of the belt system 5, work synchronously with the ones shown for rocking about the axle 10 and vertical movement in the guide slots 26. The two upstream (relative to direction D) actuators 27 are controllable independent of the two downstream actuators 27. This independent controllability is what makes two degrees of freedom α and Δz possible.

(16) In the embodiment according to FIG. 2, the mesh-belt system 5 has two endless mesh-belt sections 6 and 7 with substantially coplanar upper reaches. The two mesh belt sections 6 and 7 are each carried on four respective rollers 20 and together define a transfer gap or area 11. It is also possible to replace the two mesh belts 6 and 7 with a single mesh belt 6 to produce the configuration of FIG. 1.

(17) FIG. 3 shows a simplified version of the mesh-belt system 5 from FIG. 2 in a first operating mode. Here the two mesh belts 6 and 7 are driven in opposite directions by respective drive motors 15 and 16, so that the first nonwoven web layer 12 composed of first fibers 3 of the first melt-blowing spinneret 1 moves opposite the direction D to the right as shown in FIG. 3 and the second nonwoven web 13 of the second fibers 4 of the second melt-blowing spinneret 2 is transported to the left. What is not shown is that two nonwoven webs 12 and 13 are wound up separately from one another. So in FIG. 3, it is possible to make two completely independent nonwovens 14 are possible.

(18) In FIG. 4, a second mode of operation of the mesh-belt system 5 from FIG. 2 is shown. Here the mesh belts 6 and 7 are both run counterclockwise. The first nonwoven web layer 12 from the first fibers 3 are deflected downward in the transfer gap 11. The nonwoven web layer 12 is then moved by the web rollers 21 under the second mesh belt 7. The mesh belt rollers 21 bring the two nonwoven webs 12, 13 together so that a multilayer nonwoven 14 with a first layer 12 and a second nonwoven web layer 13 is created. The multilayer nonwoven 14 is finally consolidated by the consolidater 17. The heat of the second fibers 4 is largely dissipated before it is juxtaposed with the layer 12 of the first fibers 3. The separate guidance of the first nonwoven web layer 12 makes it possible to treat the first nonwoven web layer 12 before the nonwoven webs 12, 13 are brought together in a separate unillustrated treatment facility.

(19) In FIG. 5, in contrast to FIG. 4, the direction of the first mesh belt 6 is now clockwise. As a result, the first nonwoven web layer 12 is turned relative to the second nonwoven web 13, which is particularly important if the first nonwoven web layer 12 itself is already multilayered. In the case of FIG. 6, it is finally shown that the mesh belts 6 and 7 can move in opposite directions compared to FIG. 5, so that for example turning the second nonwoven web 13 is also possible. Thus, FIGS. 3 to 6 show the great flexibility that results when using two mesh belts 6 and 7.