APPARATUS FOR MAKING SPUNBOND FROM CONTINUOUS FILAMENTS

Abstract

An apparatus for making a nonwoven spunbond web has a spinneret for making endless filaments moving in a predetermined direction. A monomer extractor downstream from the spinneret has an upstream extractor end face directed upstream and forming a gap with a downstream spinneret end face. A cooler downstream of the extractor for the filaments has an upstream cooler end face forming with a downstream extractor end face a second gap. A stretcher downstream of the cooler for the cooled filaments has an upstream stretcher end face forming a third gap with the downstream cooler end face. The filaments are deposited on a web former by the stretcher to form the nonwoven spunbond web. A deformable seal for seals one of the gaps, and means connected to the deformable seal press the seal against the end faces forming the one gap with a variable pressure or contact face.

Claims

1. An apparatus for making a nonwoven spunbond web from endless thermoplastic filaments, the apparatus comprising: a spinneret for spinning the endless filaments moving in a predetermined filament direction and having a downstream spinneret end face directed downstream; a monomer extractor downstream in the filament direction from the spinneret and having an upstream extractor end face directed upstream and forming a gap with the downstream spinneret end face, the monomer extractor having an opposite downstream extractor end face directed downstream; a cooler downstream of the extractor for cooling the filaments and having an upstream cooler end face forming with the downstream extractor end face a second gap and an opposite downstream cooler end face; a stretcher downstream of the cooler for stretching the cooled filaments and having an upstream stretcher end face forming a third gap with the downstream cooler end face, the extractor, cooler, and stretcher forming a continuous passage extending in the filament direction; and a web former on which the filaments are deposited by the stretcher to form the nonwoven spunbond web; and a deformable seal for sealing one of the gaps; and means connected to the deformable seal for pressing the seal against the end faces forming the one gap with a variable pressure or contact face.

2. The apparatus defined in claim 1, wherein the dimension parallel to the filament direction of the first gap between the spinneret and the monomer extractor and/or the width of the second gap between the monomer extractor and the cooler and/or the width of the third gap between the cooler and the stretcher in the operating state of the apparatus is 3 to 35 mm and the seal seals across this dimension.

3. The apparatus defined in claim 2, wherein non-uniformities of the dimension the one gap are compensated for by variation of the dimension of the seal in the filament direction.

4. The apparatus defined in claim 2, wherein the seal is adjustable or deformable in the filament direction gap by 3 to 20 mm.

5. The apparatus defined in claim 1, wherein the seal extends annularly a filament flow passage extending downward ain the filament direction through the extractor, cooler, and stretcher.

6. The apparatus defined in claim 1, wherein a plurality of the seals are arranged adjacent to one another in the one gap.

7. The apparatus defined in claim 1, wherein the means for pressing can press the seal against the end faces of the respective gap with a pressure of more than 2000 Pa.

8. The apparatus defined in claim 1, wherein the seal is hollow and fillable with a fluid medium by the pressing means and adjustment of the seal is accomplished by introducing the fluid medium into the seal or by removing the fluid medium from the seal.

9. The apparatus defined in claim 1, wherein the seal is inflatable.

10. The apparatus defined in claim 1, further comprising: means usable during maintenance of the apparatus for shortening the seal in the filament direction and thereby permitting relative movement in a direction transverse to the filament direction of the end faces defining the one gap.

11. The apparatus defined in claim 10, wherein the shortening of the seal is effected by moving the seal out of contact with one of the end faces forming the one gap.

12. The apparatus defined in claim 1, wherein the means for pressing includes a spring effective in the filament direction on the seal.

13. The apparatus defined in claim 12, wherein stiffness of the spring is such that the seal is pressed in the filament direction against one of the end faces forming the one gap.

14. The apparatus defined in claim 13, wherein the spring is adjustable so as to pull the seal away from the one end face.

15. The apparatus defined in claim 1, wherein the cooler and the stretcher form a subassembly closed to entry of air from outside the passage.

16. The apparatus defined in claim 1, further comprising: a diffuser between the stretcher and the web former, forming part of the passage, receiving the filaments from the stretcher, and having secondary air inlet gaps through which secondary air passes into the diffusor.

17. The apparatus defined in claim 16, wherein the web former includes a foraminous belt on which the filaments are deposited by the diffuser, the apparatus further comprising: extractor means juxtaposed with the web former for drawing tertiary air in the filament direction through the belt and along outer surfaces of the diffusor so as to mix with primary air flowing in the filament direction through the passage.

18. The apparatus defined in claim 16, wherein the secondary air inlet gaps open into the diffuser at an angle of less than 100? to the filament flow direction.

19. The apparatus defined in claim 16, wherein a ratio of volume flows of the primary and secondary air are less than 5:1.

20. The apparatus defined in claim 16, wherein walls of the diffuser converge downstream of the secondary air inlet gaps.

21. The apparatus defined in claim 20, wherein after converging at a constriction downstream in the filament direction from the secondary air inlet gaps, the walls of the diffuser diverge.

22. The apparatus defined in claim 17, wherein the belt and a region of the belt underneath the diffuser has a width at least 20% greater than a width of the diffuser at a downstream end of the diffuser walls.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0037] 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:

[0038] FIG. 1 is a vertical section through an apparatus according to the invention,

[0039] FIG. 2 is a large-scale view of the detail indicated at II from the upper region of the apparatus according to the invention, FIG. 3 is a large-scale view III of the detail indicated at III from a lower region of the apparatus according to the invention,

[0040] FIG. 4 is a large-scale view of the detail indicated at IV in FIG. 2,

[0041] FIG. 5 is a large-scale view of the detail indicated at V in FIG. 2 and

[0042] FIG. 6 is a large-scale view like FIG. 2 with an alternative seal.

SPECIFIC DESCRIPTION OF THE INVENTION

[0043] The drawing shows an apparatus according to the invention for making spunbond of endless filaments 1, in particular thermoplastic filaments 1. The apparatus comprises a spinneret 2 for spinning the endless filaments 1 as well as a monomer extractor 4 provided in a filament flow direction FS underneath and downstream of the spinneret 2. With the monomer extractor 4, unwanted spinning-process gas, such as in particular monomers or oligomers, can be removed from the apparatus.

[0044] A cooler 3 for the filaments 1 is provided downstream of the monomer extractor 4 in the filament flow direction FS. Advantageously and here, the cooler 3 is divided into two cooling chambers 9 and 10 succeeding one another consecutively or under one another in the filament flow direction FS, so that the cooling chambers 9 and 10 preferably and here can be supplied with cooling air at different temperatures. The cooler 3 can however also have only a single cooling chamber.

[0045] A stretcher 11 for stretching the filaments 1 is provided downstream of the cooler 3 of the apparatus according to the invention. The stretcher 11 has an intermediate passage 11.1 connected upstream with the cooler 3 or its downstream cooling chamber 10 as well as a stretching shaft 11.2 extending downward and downstream from the intermediate passage 11.1. The intermediate passage 11.1 of the stretcher 11 is preferably and here configured to converge downward in the filament flow direction FS.

[0046] Between the spinneret 2 and the monomer extractor 4 is a first gap 2.1 (FIG. 2) that usually and here runs around the entire filament flow space F. In addition, a second gap 5 is provided between the monomer extractor 4 and the cooler 3 that normally and here also runs around the entire filament flow space F. Furthermore, a third gap 6 is formed between the cooler 3 or the lower cooling chamber 10 and the stretcher 11 or the intermediate passage 11.1 of the stretcher 11 which usually and here also runs around the entire filament flow space F. According to a particularly preferred embodiment and here, a first seal 2.2 is provided in the first gap 2.1 to seal the first gap 2.1 and a second seal 7 is provided in the second gap 5 to seal the second gap 5. Furthermore it is recommended and here that a third seal 8 is provided in the third gap 6 to seal the third gap 6. Sealing here means in particular that the filament forming space or filament flow space F is sealed with respect to the outside by the seals 2.2, 7, and 8 and leaks are avoided as far as possible. Preferably and here, the first seal 2.2, the second seal 7 and the third seal 8 each comprise a seal ring 2.2, 7, and 8 or annular seal running around the filament flow space F. The three seals 2.2, 7, and 8 are in particular configured as deformable seals 2.2, 7, and 8 and are in particular variable or adjustable in relation to their installation properties, in particular in relation to their pressing force, and relative to the end faces delimiting the respective gaps 2.1, 5, and 6. Adjustable here means in particular that the seals 2.2, 7, and 8 are deformable toward of the end faces defining the gaps 2.1, 5, and 6 so that the seals 2.2, 7, and 8 abut snarlingly firmly or tightly against the end faces defining the gaps 2.1, 5, and 6. The first gap 2.1, the second gap 5 and the third gap 6 can have a height h.sup.1, a height h.sup.2 and a height h.sup.3 here which lies between 5 and 30 mm. The respective seals 2.2, 7, and 8 seal the gaps 2.1, 5, and 6 each over the respective height h.sup.1 or h.sup.2 or h.sup.3. Non-uniformities of the respective heights h.sup.1, h.sup.2 or h.sup.3 of the gaps 2.1, 5, and 6 can each be compensated out by the variation/adjustment of the installation properties according to the invention, in particular the pressing force, of the seals 2.2, 7, and 8.

[0047] According to a particularly recommended embodiment of the invention and here, all three seals 2.2, 7, and 8 are each substantially or predominantly controlledly deformable in a principal direction of deformation. The principal direction of deformation is preferably and here parallel to the filament flow direction FS and vertical. Advantageously and here, the principal direction of deformation of the seals 2.2, 7, and 8 is in each case aligned toward the opposite end face of the respective gaps 2.1, 5, and 6. In FIGS. 4 and 5 only the end faces 5.1 and 6.1 of the two gaps 5 and 6 are shown. According to a recommended embodiment and here the deformation of the seals 2.2, 7, and 8 is delimited or restricted by seal guides provided next to the respective seals 2.2, 7, and 8 and extending vertically in the direction FS. In FIGS. 4 and 5 only the seal guides 7.1 and 8.1 are shown next to the seals 7 and 8.

[0048] With reference in particular to FIGS. 4 and 5, it is recommended that the second seal 7 is fixed between the monomer extractor 4 and the cooler 3 on the lower end face of the monomer extractor 4 and the principal direction of deformation of this second seal 7 is provided from the monomer extractor 4 downward toward the cooler 3. The second seal 7 then comes to rest on the upper end face 5.1 of the second gap 5 provided on the upper side of the cooler 3. According to a preferred embodiment and here, the third seal is fixed between the cooler 3 and the stretcher 11 or the intermediate passage 11.1 on the stretcher 11 or on the upper end face of the intermediate passage 11.1 and this third seal 8 can expand upwards from the intermediate passage 11.1 toward the cooler 3. This third seal 8 then comes to rest on the lower end face 6.1 of the cooler into the third gap 6. As a result of the described preferred arrangement of the seals 7 and 8 and their preferably provided principal directions of deformation, in particular deformations or sagging of the cooler 3 which take place, in particular in the CD direction, are compensated for and the gaps 5 and 6 here can be effectively sealed with the respective seals 7 and 8 according to the invention.

[0049] According to a preferred embodiment and here according to FIGS. 1 to 5 all the seal rings 2.2, 7, and 8 are elastic and can be or are filled with a gas. The gas is advantageously air. The readjustment or adjustment of the installation properties of the seals 2.2, 7, and 8 is accomplished in particular by introducing the gas or air into the seal 2.2, 7, and 8 or by withdrawing the gas or air from the seal 2.2, 7, and 8. It lies within the scope of the invention that the seals 2.2, 7, and 8 are inflatable or inflatable rings 2.2, 7, and 8. By inflating the pressing force of the seals 2.2, 7, and 8, the vertical spacing of the end faces defining the gaps 2.1, 5, and 6 can be varied and the seals 2.2, 7, and 8 can in this way compensate for irregularities in gap height h.sup.1, h.sup.2, or h.sup.3. The walls of the seals 2.2, 7, and 8 here can consist of an elastomer. Preferably the seals 2.2, 7, and 8 are annular seals or tubular seals 2.2, 7, and 8. Advantageously the seals 2.2, 7, and 8 are adapted with the proviso that a sealing takes place at a pressure in the filament flow space F of more than 2000 Pa, in particular of more than 2500 Pa.

[0050] It is recommended and here that the subassembly formed from the cooler 3 and the stretcher 11 is closed, and apart from the supply of cooling air in the cooler 3 no further supply of a fluid or air into this closed unit takes place.

[0051] The stretched filaments 1 are deposited on a foraminous belt 12 to form a nonwoven web 13. Advantageously and here a diffusor 14 is provided between the stretcher 11 and the web former 12 so that filaments 1 and primary air P pass from the stretcher 11 into the diffusor 14. Preferably and here, two opposite secondary air inlet gaps 16, 17 for introducing secondary air S are provided between the stretcher 11 or between the stretching shaft 11.2 of the stretcher 11 and the diffusor 14. Advantageously the secondary air inlet gaps 16, 17 extend over the entire CD width of the apparatus according to the invention. According to a very preferred embodiment, the secondary air is supplied through the secondary air inlet gaps 16, 17 at an inflow angle a preferably less than 60? and very preferably between 2? and 50?. In order to achieve the inflow angle ?, here suitably adapted inflow guides 18 are provided that here are configured as inflow passages 19 connected obliquely to the secondary air inlet gaps 16, 17. In this case, the inflow passages 19 form the angle a with the filament flow direction FS or with the longitudinal central axis M so that the secondary air S can flow in at the given inflow angle ?.

[0052] According to a particularly preferred embodiment, a quasi-parallel inflow of secondary air S takes place with respect to the filament flow direction FS. Advantageously the volume flow of secondary air S supplied through the secondary air inlet gaps 16, 17 can be adjusted. As a result of the inflow of the secondary air S through the secondary air inlet gaps 16, 17, primary air P is mixed with secondary air S in the diffusor 14. According to a preferred embodiment, in the region of the secondary air inlet gaps 16, 17 the ratio of the volume flows of primary air and secondary air VP/VS is less than 5:1 and preferably less than 4.5:1.

[0053] Here the diffusor 14 has a convergent diffusor section 20 downstream of or underneath the secondary air inlet gaps 16, 17. Preferably and here, this convergent diffusor section 20 is followed by a constriction 21 of the diffusor 14. In the filament flow direction FS downstream of or underneath the constriction 21 the diffusor 14 is preferably and here provided with a divergent diffusor section 22. Advantageously and here, the diffusor outlet angle p between a diffusor wall 23 of the divergent diffusor section 22 and the longitudinal central axis M of the diffusor 14 is a maximum of 25?.

[0054] The endless filaments 1 emerging from the diffusor 14 or from the divergent diffusor section 22 are deposited on the deposition device configured as a foraminous or mesh belt 12 for filament deposition or to form the nonwoven web 13. The nonwoven web 13 is the conveyed or transported away by the belt 12 in the machine direction MD. It lies within the scope of the invention that an extractor fan is provided for extracting air or process air downward through the deposition device or through the foraminous belt 12 underneath the downwardly open diffuser 14. To this end, an extraction region 25 is provided underneath the diffusor outlet 24 which preferably has a width b in the machine direction MD. The width b of the extraction region 25 is preferably and here greater than the width B of the diffusor outlet 24. According to a preferred embodiment, the width b of the extraction region 25 is at least 1.2 times, preferably at least 1.3 times the width B of the diffusor outlet 24. Here the width B of the diffusor outlet 24 is measured as the horizontal spacing between the lower ends of the diffusor walls 23 perpendicular to the direction MD. If the ends of the diffusor walls 23 of the divergent diffusor section 22 do not end on the same horizontal plane or do not end at the same vertical height, the spacing of the end of the longer diffusor wall 23 from the end an extension of the shorter diffusor wall 23 is measured at the same vertical height.

[0055] The extraction region 25 located underneath the foraminous belt 12 is delimited by two partitions 26, 27 provided extending parallel to each other in the machine direction MD, which is also the direction in which the finished nonwoven web is transported away from the diffuser 14. The width b of the extraction region 25 is measured as the distance between the two partitions 26, 27 and specifically is the spacing the upper ends or edges of the two partitions 26, 27. FIG. 3 shows that relative to the machine direction MD downstream of the deposition region of the filaments 1 the extraction region 25 projects by a first extraction section 28 beyond the diffusor outlet 24 or past the width B of the diffusor outlet 24. Furthermore preferably and here, in relation to the machine direction MD upstream of the deposition region of the filaments 1, the extraction region 25 projects oppositely by a second extraction section 29 beyond the diffusor outlet 24 or beyond the width B of the diffusor outlet 24. It can be seen in FIG. 3 that the first extraction section 28 has a width b.sub.1 and the second extraction section 29 has a width b.sub.2. In principle, it also lies within the scope of the invention that the extraction region 25 for its part is subdivided by at least one partition or by partitions. It then applies preferably however that in this extraction region 25 or in this extraction region 25 divided by partitions, the speed or the average speed of the extracted air is the same or substantially the same over the entire width of the extraction region 25.

[0056] According to a recommended embodiment of the invention, the extraction by the foraminous belt 12 takes place with the proviso that in the region of the diffusor outlet 24, tertiary air T flows along outer faces 30 of the diffusor wall 14 or the divergent diffusor section 22 toward the foraminous belt 12. According to a particularly preferred embodiment, the flows of the tertiary air T are aligned parallel or substantially parallel to the mixed flow of primary air P and secondary air S flowing toward the diffusor outlet 24 of the diffusor 14. Preferably the flows of primary air P, secondary air S and tertiary air T flow parallel or quasi-parallel through the foraminous belt 12.

[0057] FIG. 6 shows an alternative embodiment of a seal 2.2 according to the invention that here seals the first gap 2.1 between the spinneret 2 and the monomer extractor 4. This alternative seal 2.2 comprises a seal element 32 pressed by a spring 31 onto one of the end faces defining the gap 2.1 to be sealed, which sealing element is for example a sealing lip.