Apparatus and method for the manufacture of nonwoven webs and laminate

Abstract

Nonwoven laminates are made by a multi-station line comprising at least one spunbond die assembly and at least one meltblowing die assembly. Each station includes (a) a melt spinning die which can be selectively equipped with a spunbond die insert or a meltblowing die insert and (b) a moveable support structure for adjusting the proper die-to-collector distance, depending on the spunbond or meltblowing mode of operation. The multi-station line permits the selective manufacture of a variety of spunbond (S) and meltblown (M) laminates, including the S-M-S laminate.

What is claimed is:  
     
         1 . A die assembly for manufacturing thermoplastic nonwoven web which comprises 
 (a) a melt spinning assembly which includes a die body having formed therein a cavity, an air passage, and a polymer flow passage, said air passage and polymer flow passage each having an inlet in an outer surface of the die body and an outlet discharging into the cavity;    (b) a meltblowing die insert comprising (i) a die tip having formed therein a polymer flow passage and an air passage, a triangular nosepiece terminating in an outer apex, orifices formed in and spaced along the apex, the orifices being in fluid communication with the die tip polymer flow passage, and (ii) air plates mounted on each side of the nosepiece and therewith defining converging air slits which are in fluid communication with the die tip air passage; the meltblowing die insert being mountable in the cavity wherein the air passage of the die body are in fluid communication with the air passage of the die tip, and wherein the polymer flow passage of the die body is in fluid communication with the polymer flow passage of the die tip;    (c) a spunbond die insert comprising a spinning plate and polymer flow passage formed therein; said spunbond insert being mountable in the cavity wherein the air passage in the die body is blocked and wherein the polymer flow passage of the spinning plate is in fluid communication with the polymer flow passage of the die body; and    (d) means for selectively inserting the meltblowing die insert or the spunbond die insert in the cavity of the die body and for securing the selected die insert therein.    
     
     
         2 . The assembly of  claim 1  and further comprising means for delivering a polymer melt to the polymer flow passage of the die body wherein the polymer melt flows through the die body, through the flow passage of the die insert mounted in the die body cavity discharging as filaments therefrom.  
     
     
         3 . The assembly of  claim 1  wherein the meltblowing die insert is mounted in the cavity and the assembly further comprises means for delivering a polymer melt to the melt spinning assembly wherein the polymer melt flows through the polymer flow passages of the die body and the meltblowing die tip discharging as filaments from the orifices of the nosepiece, and means for delivering hot air to the melt spinning assembly air passage whereby air discharges as converging air sheets from the air slits into contact with the filaments discharging from the orifices.  
     
     
         4 . The die assembly of  claim 1  wherein the die assembly further comprising a moveable collector disposed under the melt spinning assembly for receiving and collecting filaments thereon.  
     
     
         5 . The die assembly of  claim 4  and further comprising a moveable support structure for supporting the melt spinning assembly, and means for moving the support structure vertically to selectively adjust the die-to-collector distance between an upper position for the spunbond die insert and a lower position for the meltblowing die insert.  
     
     
         6 . The assembly of  claim 1  and further comprising a carriage having mounted thereon a pair of quenching air ducts defining a quenching zone therebetween, said carriage being moveable into an operable position below the melt spinning assembly having the spunbond die insert therein and having the moveable support structure in the upper position whereby filaments extruded from the spinning plate pass through the quenching zone, said carriage being moveable to a withdrawn nonoperative position permitting the support structure to be lowered to the lower position.  
     
     
         7 . The die assembly of  claim 6  wherein the carriage further has a filament drawing device mounted thereon, said filament drawing device comprising a pair of air conduits defining a drawing zone therebetween, and being positioned below the quench ducts to receive filaments therefrom, said conduits also having air slits discharging into the drawing zone to impart downward drag forces on the filaments passign therethrough.  
     
     
         8 . An apparatus for the in-line manufacture of a laminate of thermoplastic layers comprising 
 (a) first and second side-by-side stations, each station having 
 (i) a vertically moveable support structure,  
 (ii) an extruder mounted on the moveable support structure,  
 (iii) a melt spinning die body mounted on the moveable support structure, said die body having a downwardly facing cavity formed therein, and  
 (iv) means for delivering a polymer melt from the extruder to the die body;  
   (b) a spunbond die insert mounted in the cavity of the die body of one of the stations and including means for receiving polymer melt from the die extruder and converting the melt into filaments;    (c) a meltblowing die insert mounted in the cavity of the die body of the other of the stations and including means for receiving polymer melt from the extruder and converting the melt into meltblown filaments, said spunbond die insert and said meltblowing die insert being interchangeable;    (d) a moveable filament collector positioned under the spunbond die insert and the meltblowing die insert for receiving filaments therefrom to form layers thereon; and    (e) means for selectively moving each support structure to adjust the distance of the die-to-collector for each station.    
     
     
         9 . The apparatus of  claim 8  wherein the spunbond die insert includes means for producing filaments having an average diameter of 12 to 50 microns, and the meltblowing die insert includes means for producing filaments having an average diameter of 1 to 10 microns.  
     
     
         10 . The apparatus of  claim 8  and further comprising means for bonding the two layers together.  
     
     
         11 . The apparatus of  claim 8  wherein the means for delivering polymer to the die body includes a positive displacement pump mounted on the moveable support structure.  
     
     
         12 . An in-line method of manufacturing thermoplastic nonwoven components comprising 
 (a) mounting a spunbond spinning assembly on a vertically moveable support structure having an upper position and a lower position;    (b) positioning the support structure to its upper position wherein the spunbond spinning assembly is positioned at least four feet above the lower position;    (c) positioning a quenching device and filament drawing device under the spinning assembly in vertical alignment therewith;    (d) extruding filaments from the spinning device;    (e) passing the filaments through the quenching device and a filament drawing device;    (f) depositing the filaments onto a conveyor to form a first layer;    (g) mounting a meltblowing spinning assembly on a vertically moveable support structure;    (h) positioning the support structure in its lower position wherein the meltblowing spinning assembly is from 6 inches to 3 feet above the conveyor;    (i) passing the conveyor with the first layer under the meltblowing spinning assembly;    (j) meltblowing filaments from the meltblowing spinning assembly; and    (k) depositing the meltblown filaments on top of the first layer.    
     
     
         13 . The method of  claim 12  wherein the filaments in step (d) are polyolefins selected from homopolymers and copolymers of ethylene and propylene and the filaments have an average filament diameter of in excess of 12 microns.  
     
     
         14 . The method of  claim 13  wherein the meltblown filaments are polyolefins selected from homopolymers and copolymers of ethylene and propylene and have an average diameter of 1 to 10 microns.  
     
     
         15 . The method of  claim 14  wherein the filaments are polyproylene.  
     
     
         16 . The method of  claim 12  and further comprising the step of bonding the two layers together.  
     
     
         17 . A meltblowing die comprising 
 (a) die body;    (b) a die tip mounted thereon and having a triangular nosepiece terminating in an apex, a row of orifices formed in the apex and a polymer flow passage extending through the die body, the die tip and the nosepiece for conducting a polymer melt to the orifices;    (c) air plates mounted in flanking relationship to the nosepiece and therewith defining converging air slits;    (d) a filament drawing device positioned below the row of orifices, and comprising a pair of air conduits extending parallel to the row of orifices and being spaced apart to form a drawing zone, each air conduit having a flow slit directed to discharge air downwardly into contact with the filaments passing through the drawing zone, the angle of contact being from 10 to 80° with respect to the vertical plane.    
     
     
         18 . An apparatus for forming thermoplastic filaments comprising 
 (a) an elongate melt spinning assembly for discharging a plurality of filaments downwardly therefrom;    (b) a filament drawing device comprising a pair of air conduits positioned below the melt spinning device and defining a filament drawing zone therebetween, each conduit having formed therein an air slit positioned to deliver air downwardly into the drawing zone and contact the filaments passing therethrough at an angle of 5° to 50°; and    (c) means for delivering air to each air conduit.    
     
     
         19 . A method for manufacturing meltblown and spunbond webs which comprises 
 (a) positioning an extruder and a melt spinning assembly on a vertically moveable support structure having an upper position and a lower position at least four feet below the upper position, said spinning assembly including a die body and a spunbond die insert, said extruder being connected to the melt spinning assembly;    (b) positioning the moveable support structure to the upper position;    (c) extruding filaments from the spunbond die insert;    (d) collecting the filaments on a collector to form a nonwoven layer, said filaments having an average diameter of 12 to 50 microns;    (e) discontinuing the extruding step (a) and replacing the spunbond die insert with a meltblowing die insert in the melt spinning assembly;    (f) positioning the moveable support structure to the lower position wherein the meltblowing insert is less than three feet from the collector;    (g) meltblowing filaments from the meltblowing die insert; and    (h) collecting the filaments on a collector, the filaments having an average diameter of between 1 to 10 microns.    
     
     
         20 . The method of  claim 19  and further comprising the steps of positioning an air quench ducts below the melt spinning assembly with the moveable support at its upper position to receive filaments extruded from the spunbond die insert; and removing the air quench ducts following step (e) to permit the positioning of the moveable support structure to its lower position.