Melt-blown web made of polypropylene

Abstract

A melt-blown web contains melt-blown fibers obtained by a) melt-mixing a propylene-based polymer, a first peroxide and a second peroxide at temperatures between 180° C. and 240° C., preferably between 200° C. and 220° C., wherein the first peroxide has a half-life time of 1 hour at a first temperature T 1/2 1 and the second peroxide has a half-life time of 1 hour at a second temperature T 1/2 2, wherein T 1/2 2 is higher than T 1/2 1 and b) processing the composition obtained by step a) by a melt-blown process at temperatures between 240° C. and 300° C., preferably between 245° C. and 280° C., to provide the melt-blown fibers.

1 . A melt-blown web comprising melt-blown fibers obtained by
 a) melt-mixing a propylene-based polymer, a first peroxide and a second peroxide at temperatures between 180° C. and 240° C., wherein the first peroxide has a half-life time of 1 hour at a first temperature T 1/2 1 and the second peroxide has a half-life time of 1 hour at a second temperature T 1/2 2 wherein T 1/2 2 is higher than T 1/2 1 and   b) processing the composition obtained by step a) by a melt-blown process at temperatures between 240° C. and 300° C., to provide the melt-blown fibers.   
     
     
         2 . The melt-blown web according to  claim 1 , wherein T 1/2 1 is 120 to 145° C. 
     
     
         3 . The melt-blown web according to  claim 1 , wherein T 1/2 2 is higher than 145° C. and at most 180° C. 
     
     
         4 . The melt-blown web according to  claim 1 , wherein the second peroxide has a half-life time of 0.1 hour at a temperature of 165 to 188° C. 
     
     
         5 . The melt-blown web according to  claim 1 , wherein the first peroxide is 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane and/or the second peroxide is 3,6,9-Triethyl-3,6,9-trimethyl-1,4,6 triperoxonane and/or 3,3,5,7,7-pentamethyl-1,2,4-trioxepane. 
     
     
         6 . The melt-blown web according to  claim 1 , wherein the amount of the first peroxide with respect to the propylene-based polymer is 100 to 2000 ppm and the amount of the second peroxide with respect to the propylene-based polymer is 100 to 8000 ppm. 
     
     
         7 . The melt-blown web according to  claim 1 , wherein the propylene-based polymer is a propylene homopolymer, a random propylene copolymer or a heterophasic propylene copolymer. 
     
     
         8 . The melt-blown web according to  claim 1 , wherein the propylene-based polymer has a first melt flow index MFI A  determined according to ISO1133-1:2011 at 230° C. and 2.16 kg of 0.1 to 60 dg/min. 
     
     
         9 . The melt-blown web according to  claim 1 , wherein the composition obtained by step a) has a second melt flow index MFI B  determined according to ASTM D1238-13 (2 mm die) at 190° C. and 2.16 kg of 10 to 300 dg/min. 
     
     
         10 . The melt-blown web according to  claim 1 , wherein the melt-blown fibers have a third melt flow index MFI C  determined by ASTM D1238-13 Procedure C (1 mm die) at 230° C. and 2.16 kg of 100 to 300 dg/min. 
     
     
         11 . The melt-blown web according to  claim 1 , wherein MFI C -MFI B  is at least 30 dg/min, and/or wherein MFI C -MFI B  is at most 100 dg/min, wherein MFI C  stands for the melt flow index of the melt blown fibers determined by ASTM D1238-13 Procedure C (1 mm die) at 230° C. and 2.16 kg and wherein MFI B  stands for the melt flow index of the composition obtained by step a) and determined according to ASTM D1238-13 (2 mm die) at 190° C. and 2.16 kg. 
     
     
         12 . The melt-blown web according to  claim 1 , wherein the composition obtained by step a) is formed into pellets and the pellets are subjected to step b). 
     
     
         13 . (canceled) 
     
     
         14 . An article comprising the melt-blown web according to  claim 1 . 
     
     
         15 . (canceled) 
     
     
         16 . The article of  claim 14 , wherein the article is a filter media, a medical/surgical gown, a medical/surgical drape, a medical/surgical face mask, a diaper, a feminine hygiene product, a sanitary napkin, an adult incontinence product, an absorbent mat, a wipe, an oil containment boom, a protective apparel, a mask, a wet tissues articles used in electronics, a battery separator, a cable wrap, an adhesives, an insulators, or a composite non-woven.