Apparatus for making a spunbond web from filaments

Abstract

An apparatus for continuously making a spunbond web of filaments comprises a spinneret, a cooling chamber into which process air for can be introduced for the purpose of cooling the filaments, a monomer suction device between a spinneret and cooling chamber, a stretcher and a deposition device for depositing the filaments of the spunbond web. The cooling chamber is divided into two cooling compartments, and process air can be suctioned out from a first upper cooling compartment at a volumetric flow rate (V.sub.M) to a monomer suction device. Process air exits from the first upper cooling compartment at a volumetric flow rate (V.sub.1) into a second lower cooling compartment and from the first upper cooling compartment at a volumetric flow rate (V.sub.1) into a second lower cooling compartment. A ratio (V.sub.M/V.sub.1) is 0.1 to 0.35.

Claims

1. An apparatus for making a spunbond web of filaments, the apparatus comprising: a spinneret generating thermoplastic filaments in a direction, a cooling chamber downstream from the spinneret subdivided into upper and lower cooling compartments, means for introducing process air for cooling the filaments into the chamber, a monomer suction device between the spinneret and the cooling chamber for receiving the filaments from the spinneret and feeding the filaments to the cooling chamber, a stretcher downstream of the monomer suction device and receiving the filaments from the cooling chamber, a deposition device downstream of the stretcher for deposition of the filaments by the stretcher as the web, recirculating means for withdrawing a portion of the process air from the upper cooling compartment at a volumetric flow rate of V.sub.M, feeding the withdrawn portion of the process air to the monomer suction device, feeding another portion of the process air at a volumetric flow rate V.sub.1 into the lower cooling compartment such that a volumetric flow-rate ratio V.sub.M/V.sub.1 is 0.1 to 0.35, and withdrawing process air at a volumetric flow rate V.sub.2 from the lower cooling chamber portion such that a volumetric flow rate V.sub.1/V.sub.2 is 0.1 to 0.45.

2. The apparatus according to claim 1, further comprising: an air supply cabin positioned next to the cooling chamber and divided into upstream and downstream cabin sections, the recirculating means introducing process air into the upper cooling compartment from the upstream cabin section and into the lower cooling compartment from the downstream cabin section.

3. The apparatus according to claim 1, wherein a distribution of nozzle holes of the spinneret is homogeneous everywhere or across the entire nozzle plate of the spinneret.

4. The apparatus according to claim 1, wherein a spacing between the spinneret and the cooling chamber can be varied.

5. The apparatus according to claim 1, wherein air from outside is blocked from entry into the cooling chamber and at the transition area between the cooling chamber and the stretcher.

6. The apparatus according to claim 1, further comprising: a diffuser between the stretcher and the deposition unit.

7. An apparatus for making a spunbond web, the apparatus comprising: means for supplying polypropylene having an average isotactic sequence length of at least 65 and an onset temperature of at least 120°; a spinneret having a nozzle plate forming a plurality of nozzle holes homogeneously distributed across the entire nozzle plate and connected to the means for heating for receiving the heated polypropylene and extruding filaments of the heated polypropylene through the homogeneously distributed nozzle holes such that the filaments travel in a flow direction and are spaced apart homogeneously in a direction transverse to the flow direction; a monomer suction device downstream of the spinneret and through which the homogeneously spaced and extruded filaments move in the flow direction; a cooling chamber downstream of the monomer suction device and divided into upper and lower cooling compartments through which the filaments move in the direction after exiting the monomer suction device; blower means for feeding cool process air into the cooling chamber to cool the filaments in the compartments thereof, sucking a portion from the upper cooling compartment and into the monomer suction device at a volumetric flow rate V.sub.M, feeding another portion of the process air from the upper compartment at a volumetric flow rate V.sub.1 into the lower cooling compartment, withdrawing process air from the lower cooling compartment at a volumetric flow rate V.sub.2; control means connected to the blower means for setting the flow rates relative to each other such that a volumetric flow-rate ratio V.sub.M/V.sub.1 is 0.1 to 0.3 and a volumetric flow-rate ratio V.sub.1/V.sub.2 is 0.1 to 0.45; a stretcher downstream of the lower cooling compartment for receiving and stretching the filaments therefrom; and a deposition device downstream of the stretcher for receiving the stretched filaments.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, the invention is explained in greater detail based on a drawing illustrating only one sample design. It shows the following in schematic drawing:

(2) FIG. 1 a vertical section through the apparatus according to the invention and

(3) FIG. 2 an enlarged section of the detail shown at II in FIG. 1.

SPECIFIC DESCRIPTION OF THE INVENTION

(4) The figures show an apparatus for continuous production of a spunbond web of filaments of thermoplastic. The apparatus exhibits, first of all, a spinneret 1 with a nozzle plate 2 and nozzle holes therein for spinning the filaments that are not depicted. The spun filaments are then run past a monomer suction device 3 positioned below spinneret 1. This monomer suction device 3 is used to remove objectionable gasses from the system during the spinning process. The monomer suction device 3 exhibits a sucking chamber 4 as well as an exhaust ventilator 5 connected to the sucking chamber 4. A sucking slit 6 for sucking up the gasses is included in the lower region of the sucking chamber 4. Most practically, the sucking chamber 4 will be positioned both to the right and left of the filament formation space, as shown in the design example. The left half of the sucking chamber 4 is also connected to sucking ventilator 5.

(5) A cooling chamber 7 into which process air for cooling the filaments can be introduced is positioned below the spinneret 1 and below the monomer suction device 3. Preferably, the cooling chamber 7 will be divided into an initial, upper cooling chamber 7a and a second, lower cooling chamber 7b, as shown in the design example. Most practically, and as shown in the design example, an air supply chamber 8 will be positioned next to the cooling chamber 7 that advisably and as shown in the design example, will be divided into an upper compartment 8a and a lower compartment 8b. Preferably and as shown in the design example, process air of various volumetric flow rates can be fed in from the two compartments 8a and 8b. Most practically and as shown in the design example, a blower 9a and 9b for feeding in process air will be connected to the compartments 8a and 8b. The scope of the invention includes that the infed volumetric flow rates of process air can be controlled. The scope of the invention also includes that the compartments 8a and 8b be positioned both to the right and left of the cooling chamber 7. The left halves of compartments 8a and 8b are also connected to the corresponding blowers 9a and 9b.

(6) The invention is based on the recognition that process air can be or is sucked from the first, upper cooling compartment 7a at a volumetric flow rate V.sub.M via the monomer suction device 3 positioned above the cooling chamber 7. The process air leaves the first, upper cooling compartment 7a toward the second cooling compartment 7b at a volumetric flow rate V.sub.1. According to the invention, the ratio of the volumetric flow rates V.sub.M/V.sub.1 is 0.1 0.3 and preferably 0.12 to 0.25. The process air leaves the second, lower cooling compartment 7b at a volumetric flow rate V.sub.2. The flow volume ratio V.sub.1/V.sub.2 is preferably 0.1 to 0.5.

(7) It can be seen in FIG. 1 that the cooling chamber 7 is connected to the intermediate passage 10, as shown in the design example. This intermediate passage 10 reaches to pulling under passage 11 of the stretcher 12. Most practical and as shown in FIG. 1 of the design example, the intermediate passage 10 runs together in a vertical, wedge-shaped cut from the outlet of cooling chamber 7 to the inlet of the pulling under passage 11, and preferably and as shown in the design example with the entry width of the pulling under passage 11. Preferably and as shown in the design example, a laying unit 13 is positioned below the stretcher 12. In the design example, this laying unit 13 has two diffusers 14 and 15. It can be seen that each of these diffusers 14 and 15 has a diverging shape or is designed with diverging walls in the lower area. Preferably and as shown in the design example, a continuous, moving conveyor belt 16 for depositing the filaments and/or the spunbond web is provided below the laying unit 13.

(8) It can be seen in FIG. 1 that, with the exception of the infeed of process air to the cooling chamber 7, no air supply takes place in the area of the cooling chamber 7, the intermediate passage 10, and the laying unit 13. This means that operations are performed in a closed system. FIG. 1 also shows that the spacing between the spinneret 1 and/or between the nozzle plate 2 and the cooling chamber 7 can be set and varied according to the recommended design form. Most practical and as shown in the design example, the vertical height of spinneret 1 can be set.