Optimized Polymer Rheology for High Extensibility Spunbond Filaments

Abstract

A method for producing spunbond fibers including providing a base polypropylene having initial rheologic properties with high molecular weight average (Mw) and melt flow rate (MFR) following the correlation Mw>270-2*MFR, where Mw is measured in kilodaltons (kDa) and MFR is measured in accordance with ASMT1238, 230C/2.16 kg, mixing the base polypropylene with an additive at a concentration to produce an adjusted base polypropylene with adjusted rheologic properties following the correlation Mw>260-MFR, with MFR in a range of 100 g/10 min (230C/2.16 kg) to 250 g/10 min (230C/2.16 kg), and melt-extruding the adjusted base polypropylene at cabin pressures above 7000 Pa to produce highly extensible filaments.

1 . A method for producing spunbond fibers comprising:
 a. providing a base polypropylene having initial rheologic properties with high molecular weight average (Mw) and melt flow rate (MFR) following the correlation Mw>270-2*MFR, where Mw is measured in kilodaltons (kDa) and MFR is measured in accordance with ASMT1238, 230C/2.16 kg;   b. mixing the base polypropylene with an additive at a concentration to produce an adjusted base polypropylene with adjusted rheologic properties following the correlation Mw>260-MFR, with MFR in a range of 100g/10 min (230C/2.16 kg) to 250 g/10 min (230C/2.16 kg); and   c. melt-extruding the adjusted base polypropylene at cabin pressures above 7000 Pa to produce highly extensible filaments;   d, wherein the produced filaments have an average denier below 1.5.   
     
     
         2 . The process of  claim 1 , wherein the additive comprises at least one of a stearate metallic salt oxidation catalyst or a visbreaking additive. 
     
     
         3 . The process of  claim 1 , wherein the initial rheologic properties of the base polypropylene comprises a Mw above 200 kDa at an MFR of 35 g/10 min (230C/2.16 kg). 
     
     
         4 . The process of  claim 1 , wherein the initial rheologic properties of the base polypropylene comprises a Mw above 230 kDa at an MFR of 20 g/10 min (230C/2.16 kg). 
     
     
         5 . The process of  claim 1 , wherein adjusted rheologic properties of the adjusted base propylene comprises a Mw above 140 kDa at an MFR of 120 g/10 min (230C/2.16 kg). 
     
     
         6 . The process of  claim 1 , wherein the adjusted rheologic properties of the adjusted base propylene comprises and a Mw above 160 kDa at an MFR of 100 g/10 min (230C/2.16 kg). 
     
     
         7 . The process of  claim 1 , further comprising mixing the base polypropylene with other additives comprising pigments, slip additives, surfactants, or polymer modifiers before or after the step of melt extruding to adjust filament and nonwoven material properties. 
     
     
         8 . The process of  claim 1 , wherein the filaments have a monofilament configuration or alternatives to monofilament configurations comprising alternative types selected from the group consisting of bicomponent core/sheath, bicomponent side by side, trilobal and islands-in-the-sea. 
     
     
         9 . The process of  claim 1 , wherein the initial rheologic properties of the base polypropylene comprises an MFR within a range of 10 to 60 g/10 min (230C/2.16 kg). 
     
     
         10 . The process of  claim 1 , wherein the initial rheologic properties of the base polypropylene comprises an MFR within a range of 1 to 100 g/10 min (230C/2.16 kg). 
     
     
         11 . The process of  claim 1 , wherein the additive is a visbreaking additive mixed with the base polypropylene at an active compound concentration within a range of 50 and 500 ppm. 
     
     
         12 . The process of  claim 1 , wherein the additive is a visbreaking additive mixed with the base polypropylene at an active compound concentration within a range of 25 and 750 ppm. 
     
     
         13 . The process of  claim 1 , wherein the additive is a visbreaking additive mixed with the base polypropylene at an active compound concentration within a range of 10 and 2500 ppm. 
     
     
         14 . The process of  claim 1 , wherein the adjusted rheologic properties of the adjusted base polypropylene comprises an MFR within a range of 75 to 300 g/10 min (230C/2.16 kg). 
     
     
         15 . The process of  claim 1 , wherein the adjusted rheologic properties of the adjusted base polypropylene comprises an MFR within a range of 50 to 400 g/10 min range (230C/2.16 kg). 
     
     
         16 . The process of  claim 1 , wherein the adjusted base polypropylene is melt-extruded at a throughput between 180 and 280 kg/h/m. 
     
     
         17 . The process of  claim 1 , wherein the adjusted base polypropylene is melt-extruded at throughputs between 150 kg/h/m and 300 kg/h/m. 
     
     
         18 . The process of  claim 1 , wherein the adjusted base polypropylene is melt-extruded at a throughput above 300 kg/h/m and below 150 kg/h/m. 
     
     
         19 . The process of  claim 1 , wherein the adjusted base polypropylene is melt-extruded at cabin pressures between 8000 and 13000 Pa. 
     
     
         20 . The process of  claim 1 , wherein the adjusted base polypropylene is melt-extruded at cabin pressures between 7000 and 15000 Pa. 
     
     
         21 . The process of  claim 1  wherein the adjusted base polypropylene is melt-extruded at cabin pressures above 15000 Pa. 
     
     
         22 . The process of  claim 1 , wherein the average denier is between 1.2 and 0.8. 
     
     
         23 . The process of  claim 1 , wherein the average denier is between 1.5 and 0.6. 
     
     
         24 . The process of  claim 1 , wherein the average denier is below 0.6. 
     
     
         25 . A method for producing spunbond fibers comprising:
 a. mixing a base polypropylene with an additive to obtain an adjusted base polypropylene with reduced viscosity and increased melt flow rate (MFR); and   b. melt extruding the adjusted base polypropylene to produce highly extensible filaments.   
     
     
         26 . The process of  claim 25 , further comprising mixing the base polypropylene with other additives comprising pigments, slip additives, surfactants, or polymer modifiers before or after the step of melt extruding to adjust filament and nonwoven material properties at an amount above 3 wt % based on the weight of polypropylene so that the produced filaments have a denier below 1.8. 
     
     
         27 . The process in  claim 26 , wherein the denier is below 1.6. 
     
     
         28 . The process in  claim 26 , wherein the denier is below 1.4. 
     
     
         29 . The process of  claim 25 , wherein the filaments have a monofilament configuration or alternatives to monofilament configurations comprising alternative types selected from the group consisting of bicomponent core/sheath, bicomponent side by side, trilobal and islands-in-the-sea, and the alternatives to monofilament configurations are used so that the produced filaments have a denier below 1.8. 
     
     
         30 . The process in  claim 29 , wherein the denier is below 1.6. 
     
     
         31 . The process in  claim 29 , wherein the denier is below 1.4. 
     
     
         32 . The process in  claim 29 , further comprising mixing the base polypropylene with other additives comprising pigments, slip additives, surfactants, or polymer modifiers before or after the step of melt extruding to adjust filament and nonwoven material properties. 
     
     
         33 . The process of  claim 25 , wherein the filaments have a polypropylene/polyethylene bicomponent configuration and the filaments produced are under 1.8 denier. 
     
     
         34 . The process in  claim 33 , wherein the filaments produced are under 1.6 denier. 
     
     
         35 . The process in  claim 33 , wherein the filaments produced are under 1.4 denier. 
     
     
         36 . A polypropylene spunbond nonwoven comprising the following properties:
 a. a basis weight within a range of 5 and 100 gsm;   b. reduced air permeability of at least 15% lower than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities;   c. enhanced machine direction tensile strength (MDT) of at least 15% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities; and   d. enhanced cross direction tensile strength (CDT) of at least 10% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities.   
     
     
         37 . A polypropylene spunbond nonwoven with basis weight within a range of 13 to 15 gsm and air permeability within a range of 240 to 200 m3/m2/min. 
     
     
         38 . A polypropylene spunbond nonwoven with basis weight within a range of 13 to 15 gsm and a machine direction tensile strength (MDT) within a range of 6 to 10 N/cm. 
     
     
         39 . A polypropylene spunbond nonwoven with basis weight within a range of 26 to 31 gsm and air permeability within a range of 110 to 40 m3/m2/min. 
     
     
         40 . A polypropylene spunbond nonwoven with basis weight within a range of 26 to 31 gsm and a machine direction tensile strength (MDT) within a range of 14.5 to 18N/cm and a CDT between 6 and 10 N/cm. 
     
     
         41 . A polypropylene spunbond nonwoven comprising the following properties:
 a. a basis weight within a range of 20 and to 100 gsm;   b. reduced air permeability of at least 20% lower than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities;   c. enhanced machine direction tensile strength (MDT) of at least 20% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities;   d. enhanced cross direction tensile strength (CDT) of at least 15% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities.   
     
     
         42 . A method for producing spunbond or SMS fabric in a high-speed continuous filament spinning line comprising:
 mixing a base recycled polypropylene with an additive to reduce viscosity and increase melt flow rate (MFR) of the base recycled polypropylene, the base recycled polypropylene having an MFR below 10 g/10 min (230C/2.16 kg).   
     
     
         43 . A method for producing spunbond or SMS fabric in a high-speed continuous filament spinning line comprising:
 mixing a base recycled polypropylene with an additive to reduce viscosity and increase melt flow rate (MFR) of the base recycled polypropylene, the base recycled polypropylene having an MFR below 5 g/10 min (230C/2.16 kg).   
     
     
         44 . A process of making an SMS composite fabric by producing fine fiber spunbond layers in accordance with the process of  claim 1  and a meltblown layer, wherein:
 a. the SMS composite fabric has enhanced hydrohead of at least 15% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities; 
 b. the SMS composite fabric has reduced air permeability of at least 15% lower than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities. 
 
     
     
         45 . A process of making an SMS composite fabric by producing fine fiber spunbond layers in accordance with the process of  claim 1  and a meltblown layer, wherein:
 a. the SMS composite fabric has enhanced hydrohead of at least 30% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities; 
 b. the SMS composite fabric has reduced air permeability of at least 30% lower than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities. 
 
     
     
         46 . A process of making an SMS composite fabric with improved properties by producing fine fiber spunbond layers in accordance with the process of  claim 1  and a meltblown layer, wherein:
 a. the SMS composite fabric has enhanced hydrohead of at least 50% higher than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities; 
 b. the SMS composite fabric has reduced air permeability of at least 50% lower than a control web with same basis weight and processed at the same conditions except cabin pressure is ran at highest possible before triggering instabilities.