Semi-continuous filaments including a crystalline polyolefin and a hydrocarbon tackifier resin, and process for making same

Abstract

Nonwoven webs including one or more semi-continuous filaments made of a mixture including from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin. The at least one semi-continuous filament exhibits molecular orientation, and at least one of the crystalline polyolefin (co)polymer or the nonwoven web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g. A process for making the semi-continuous filaments and nonwoven webs is also disclosed.

1 . A nonwoven web, comprising:
 at least one semi-continuous filament comprising from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin, wherein the at least one semi-continuous (co)polymeric filament exhibits molecular orientation, and further wherein the nonwoven web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.   
     
     
         2 . The nonwoven web of  claim 1 , wherein the at least one crystalline polyolefin (co)polymer is selected from the group consisting of polyethylene, isotactic polypropylene, syndiotactic polypropylene, isotactic polybutylene, syndiotactic polybutylene, poly-4-methyl pentene, and mixtures thereof. 
     
     
         3 . The nonwoven web of  claim 2 , wherein the at least one crystalline polyolefin (co)polymer exhibits a Heat of Fusion measured greater than 50 Joules/g. 
     
     
         4 . The nonwoven web of  claim 1 , wherein the at least one hydrocarbon tackifier resin is a saturated hydrocarbon. 
     
     
         5 . The nonwoven web of  claim 1 , wherein the at least one hydrocarbon tackifier resin is selected from the group consisting of C 5  piperylene derivatives, C 9  resin oil derivatives, and mixtures thereof. 
     
     
         6 . The nonwoven web of  claim 1 , wherein the at least one hydrocarbon tackifier resin makes up from 2% to 40% by weight of the (co)polymeric filaments. 
     
     
         7 . The nonwoven web of  claim 6 , wherein the at least one hydrocarbon tackifier resin makes up from 5% to 30% by weight of the (co)polymeric filaments. 
     
     
         8 . The nonwoven web of  claim 7 , wherein the at least one hydrocarbon tackifier resin makes up from 7% to 20% by weight of the (co)polymeric filaments. 
     
     
         9 . The nonwoven web of  claim 1 , wherein the at least one (co)polymeric filament exhibits a mean Actual Filament Diameter of less than 5 micrometers as determined using the Optical Microscopy Test. 
     
     
         10 . The nonwoven web of  claim 1 , wherein the at least one (co)polymeric filament exhibits a mean Actual Filament Diameter of from about 4 micrometers to about 10 micrometers, inclusive, as determined using the Optical Microscopy Test. 
     
     
         11 . The nonwoven web of  claim 1 , further comprising between 0 to about 30% of at least one plasticizer. 
     
     
         12 . The nonwoven web of  claim 11 , wherein the at least one plasticizer is selected from the group consisting of oligomers of C 5  to C 14  olefins, and mixtures thereof. 
     
     
         13 . The nonwoven web of  claim 1 , wherein the nonwoven web exhibits a Maximum Load in the Machine Direction of at least 40 Newtons as measured using the Tensile Strength Test. 
     
     
         14 . The nonwoven web of  claim 1 , wherein the nonwoven web exhibits a Basis Weight of from 1 gsm to 400 gsm, inclusive, optionally wherein the Basis Weight is from 1 gsm to 50 gsm. 
     
     
         15 . The nonwoven web of  claim 1 , wherein the nonwoven web exhibits a Stiffness of at least 800 mg as measured using the Stiffness Test. 
     
     
         16 . A process for making a nonwoven web, comprising:
 a) heating a mixture of about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin to at least a Melting Temperature of the mixture to form a molten mixture;   b) extruding the molten mixture through at least one orifice to form at least one semi-continuous filament;   c) attenuating the at least one semi-continuous filament to draw and molecularly orient the at least one semi-continuous filament; and   d) cooling the at least one semi-continuous filament to a temperature below the Melting Temperature of the molten mixture to form a nonwoven web, wherein the at least one semi-continuous (co)polymeric filament exhibits molecular orientation, and further wherein at least one of the crystalline polyolefin (co)polymer or the nonwoven web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g.   
     
     
         17 . The process of  claim 16 , wherein extruding the mixture through at least one orifice to form the at least one semi-continuous filament is accomplished using a melt-spinning process. 
     
     
         18 . The process of  claim 16 , further comprising at least one of addition of a plurality of staple filaments to the at least one semi-continuous filament, or addition of a plurality of particulates to the at least one semi-continuous filament. 
     
     
         19 . The process of  claim 16 , further comprising collecting the at least one semi-continuous filament as the nonwoven web on a collector. 
     
     
         20 . The process of  claim 19 , further comprising processing the collected nonwoven web using a process selected from the group consisting of autogenous bonding, through-air bonding, electret charging, calendering, embossing, needle-punching, needle tacking, hydroentangling, or a combination thereof.