Apparatus for making a spunbond nonwoven

Abstract

An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics has a spinneret for spinning and emitting the filaments in a travel direction, a cooler downstream of the spinneret for cooling the spun filaments, and a stretcher downstream of the cooler for stretching the filaments. An intermediate passage extending in the travel direction between the cooler and the stretcher has upstream and downstream converging passage sections. The upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments. A ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section is 1.5 to 5.5. A ratio of an inlet width b.sub.E, to an outlet width b.sub.A, of the downstream passage section is 1 to 4.

Claims

1. An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics, the apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, an opening angle between an upper passage wall of the upstream passage section and a center plane extending in the travel direction through the intermediate passage being 25 to 60.

2. The apparatus defined in claim 1, wherein the intermediate passage connects the cooler and the stretcher directly to one another.

3. The apparatus defined in claim 1, wherein the cooler, the intermediate passage and the stretcher form a closed system and there is no additional supply of air into this closed system other than cooling air from the cooler.

4. The apparatus defined in claim 1, wherein a ratio of a length in the travel direction of the upstream passage section to a length in the travel direction of the downstream passage section is 1:3 to 1:20.

5. An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics, the apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, an opening angle between an upper passage wall of the downstream passage section and the center plane being 0.25 to 12.

6. An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics, the apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, the ratio B.sub.E/B.sub.A being larger than or equal to the ratio b.sub.E/b.sub.A.

7. An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics, the apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, and a product of the ratio B.sub.E/B.sub.A and a length in the travel direction of the upstream section being 200 to 500.

8. An apparatus for making a spunbond nonwoven from monofilaments of thermoplastic synthetics, the apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, a product of the ratio b.sub.E/b.sub.A and a length in the travel direction of the downstream passage section being 1600 to 3250.

9. The apparatus defined in claim 1, wherein a ratio of the inlet width B.sub.E of the upstream passage section to a total length in the travel direction of the intermediate passage is 0.15 to 0.30.

10. The apparatus defined in claim 1, further comprising: a monomer aspirator immediately downstream of the spinneret for suction removal of gases generated by spinning of the monofilaments.

11. The apparatus defined in claim 10, wherein the monomer aspirator is set up such that different volume flows of gas can be removed by suction on opposing sides spaced apart transversely of the travel direction and flanking the filaments from the spinneret.

12. The apparatus defined in claim 1, wherein the cooler has upper and lower compartments one after the other in the travel direction, with cooling air at a different temperatures and convective thermal heat dissipation capacities.

13. The apparatus defined in claim 1, further comprising: a diffuser through which the filaments pass in the travel direction immediately downstream of the stretcher; and a deposition element downstream of the diffuser and receiving the filaments therefrom.

14. A method of making a spunbond nonwoven using an apparatus comprising: a spinneret for spinning and emitting the filaments in a travel direction; a cooler downstream in the travel direction of the spinneret for cooling the spun filaments; a stretcher downstream in the travel direction of the cooler for stretching the filaments; structure forming an intermediate passage extending in the travel direction between the cooler and the stretcher, the intermediate passage having upstream and downstream converging passage sections provided one after the other in the travel direction of the filaments, the upstream passage section in the travel direction of the filaments having a shorter length than the downstream passage section in the travel direction of the filaments, a ratio B.sub.E/B.sub.A of an inlet width B.sub.E to an outlet width B.sub.A of the upstream passage section being 1.5 to 5.5, a ratio of an inlet width b.sub.E to an outlet width b.sub.A of the downstream passage section being 1 to 4, an opening angle between an upper passage wall of the upstream passage section and a center plane extending in the travel direction through the intermediate passage being 25 to 60 the method including the step of: moving the filaments through the apparatus at a throughput rate of 100 to 350 kg/h/m.

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 vertical section through an apparatus according to the invention;

(3) FIG. 2 is a large-scale view of the detail shown at II in FIG. 1 of the intermediate passage according to the invention; and

(4) FIG. 3 is a large-scale view of the detail shown at III in FIG. 1.

SPECIFIC DESCRIPTION OF THE INVENTION

(5) As seen in FIG. 1, an apparatus according to the invention for making a spunbond nonwoven 1 from monofilaments 2 creates monofilaments 2 made entirely or essentially of thermoplastic synthetic resin. In this illustrated embodiment, the monofilaments 2 are spun using a spinneret 3 and, in a filament-forming zone 4 below the spinneret 3, they are passed through a monomer aspirator 5 for vacuum removal of gases formed during the spinning process. A cooler 6 downstream from and/or below this monomer aspirator 5 as seen in the travel direction of the filament cools the monofilaments 2. Advantageously and in the illustrated embodiment, this cooler 3 has an air-supply chamber, preferably subdivided into two compartments 7, 8 in the illustrated embodiment. Cooling air at an adjustable temperature can be supplied in the direction of the filament bundle 9 advantageously and in the illustrated embodiment.

(6) The intermediate passage 10 according to the invention is connected to the cooler 6 downstream in the travel direction of the filaments. The intermediate passage 10 according to the invention is subdivided into two converging passage sections 11, 12 provided one below the other or after the other and converging in the travel direction of the filaments. The upstream and/or upper passage section 11 in the travel direction of the filaments has a shorter length (in the travel direction of the filaments) than the downstream and/or lower passage section 12 in the travel direction of the filaments. Preferably and in the illustrated embodiment, the ratio of the inlet width B.sub.E to the outlet width B.sub.A of the upstream passage section 11 is 2.25 to 2.75. The ratio of the inlet width b.sub.E to the outlet width b.sub.A of the downstream passage section 12 according to the recommendation and in the illustrated embodiment has a value of 1.9 to 2.7. The ratio of the length L of the upstream passage section 11 to the length l of the downstream passage section 12 is advantageously and in the illustrated embodiment 1:7 to 1:9.

(7) The aperture angle between the upper passage wall 13 of the upstream and/or upper passage section 11 and the center plane M running through the intermediate passage 10 very preferably and in the illustrated embodiment amounts to 30 to 50. A center plane M extends transversely, preferably perpendicularly to the machine direction (MD) of the apparatus in this illustrated embodiment. Advantageously and in the illustrated embodiment, the aperture angle between the lower passage wall 14 of the downstream and/or lower passage section 12 and the center plane M running through the intermediate passage 10 amounts to M 0.4 to 6.

(8) According to the recommendation and in the illustrated embodiment, a lower passage 15 of the stretcher 16 is connected to the intermediate passage 10 according to the invention. Preferably and in the illustrated embodiment, the assembly of the cooler 6, the intermediate passage 10 and the stretcher 16 and/or the lower passage 15 is designed as a closed system and in addition to the supply of cooling air in the cooler 6, there is no other air supply in this closed system.

(9) Advantageously and in the illustrated embodiment, two diffusers 17, 18 through which the monofilaments 2 are passed are provided downstream from and/or below the stretcher 16 in the travel direction of the filaments. According to a particularly preferred embodiment and in the illustrated embodiment, a secondary air inlet gap and/or an ambient air inlet gap 25 for the admission of ambient air is/are provided between the two diffusers 17 and 18. Preferably and in the illustrated embodiment, the monofilaments 2 are deposited on a support surface designed as a mesh belt 19 to form the spunbond nonwoven web downstream from the diffusers 17, 18. It is within the scope of the invention for the spunbond nonwoven to then be passed through a calendar 20 for stabilization and/or pre-stabilization.

(10) According to a preferred embodiment and in the illustrated embodiment, the monomer aspirator 5 has two opposing CD vacuum ports 21, 22 provided one after the other in the machine direction (MD), each extending transversely to the machine direction and opposite one another with respect to the spinning zone. These CD vacuum ports are preferably designed as CD vacuum gaps 23, 24 in the illustrated embodiment. Here a higher volume flow is removed by suction through the rear CD vacuum gap 24, as seen in the machine direction, than through the front CD vacuum gap 23 in the machine direction. Preferably and in the illustrated embodiment, the vertical gap height h.sub.A of the rear CD vacuum gap 24 in the machine direction is greater than the vertical gap height h.sub.E of the front CD vacuum gap 23 in the machine direction. According to one embodiment of the invention and in the illustrated embodiment, the gap height h.sub.A of the rear CD vacuum gap 24 in the machine direction is more than twice the gap height h.sub.E of the CD vacuum gap 23 which is at the front in the machine direction.