Tempered Melt-Blown Nonwoven Having a High Compression Hardness

Abstract

The invention relates to a method for producing a tempered melt-blown nonwoven, comprising the following steps: a) producing a melt-blown nonwoven preferably by applying flowing air to the outside of polymer melt extruded through a nozzle and stretching said polymer melt before the filaments thereby formed are laid and cooled on a carrier, which is preferably a double suction drum, and b) tempering at least one section of the melt-blown nonwoven produced in step a) at a temperature that lies between the glass transition temperature and 0.1° C. below the melt temperature of the filaments of the melt-blown nonwoven, the melt-blown nonwoven having a weight per unit area of 100 to 600 g/m2, a density of 5 to 50 kg/m3 and a compression hardness at 60% compression, measured according to DIN EN ISO 3386, of at least 2 kPa. The invention further relates to a tempered melt-blown nonwoven produced by means of said method, preferably a tempered voluminous melt-blown nonwoven. Said tempered melt-blown nonwoven is characterized by a significantly increased compression hardness in comparison with an untempered melt-blown nonwoven.

1 - 15 . (canceled) 
     
     
         16 . An annealed meltblown nonwoven fabric, obtainable by means of a method in which at least a portion of the meltblown nonwoven fabric ( 15 ) is subsequently annealed at a temperature between the glass transition temperature and 0.1° C. below the current melting temperature of the filaments of the meltblown nonwoven fabric ( 15 ),
 wherein 
 the meltblown nonwoven fabric ( 15 ) is composed of a polyolefin, and the meltblown nonwoven fabric ( 15 ) has a weight per unit area of from 100 to 600 g/m 2 , a density of from 5 to 50 kg/m 3 , and a compression hardness at 60% compression of at least 2 kPa as measured according to DIN EN ISO 3386. 
 
     
     
         17 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is annealed at a temperature between 20° C. and 1° C. below the current melting temperature of the filaments of the meltblown nonwoven fabric ( 15 ).   
     
     
         18 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is annealed at the temperature for 1 minute to 10 days.   
     
     
         19 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is annealed through exposure to hot air and/or superheated steam.   
     
     
         20 . The meltblown nonwoven fabric as set forth in  claim 19 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is annealed in a furnace ( 10 ) having at least one blast box ( 16 ,  16 ′) and at least one suction box ( 18 ), the at least one blast box ( 16 ,  16 ′) being arranged such that the hot air can be blown into the meltblown nonwoven fabric ( 15 ), and the at least one suction box ( 18 ) being arranged such that air flowing through the meltblown nonwoven fabric ( 15 ) can be extracted.   
     
     
         21 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) has a weight per unit area of from 100 to 400 g/m 2 .   
     
     
         22 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is a voluminous meltblown nonwoven fabric ( 15 ) having a density of from 7 to 40 kg/m 3 .   
     
     
         23 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) is composed of filaments that are made of a polypropylene and/or polyethylene.   
     
     
         24 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the thickness of the meltblown nonwoven fabric ( 15 ) is from 6 to 50 mm.   
     
     
         25 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   i) the meltblown nonwoven fabric ( 15 ) is annealed in a mold ( 20 ) for the purpose of reshaping it during annealing, the mold ( 20 ) being embodied at least partially as a screen ( 22 ,  22 ′), so that the meltblown nonwoven fabric ( 15 ) can be flowed through and/or flowed around by hot air and/or with superheated steam during annealing, and/or ii) the meltblown nonwoven fabric ( 15 ) is transferred to a mold ( 20 ) after heating for the purpose of reshaping it, in which case the meltblown nonwoven fabric ( 15 ) is cooled in the mold in order to conclude the annealing process.   
     
     
         26 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   at least one spacer is provided in the meltblown nonwoven fabric ( 15 ) that is arranged in the direction of thickness of the meltblown nonwoven fabric ( 15 ) and, as a result of permanent molding, has a length that is greater than the length of the meltblown nonwoven fabric ( 15 ).   
     
     
         27 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) that is subsequently annealed was manufactured by applying flowing air to the outside of a polymer melt that is extruded through a die and drawing said polymer melt before the filaments that are formed in this way are placed onto a carrier and cooled.   
     
     
         28 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the meltblown nonwoven fabric ( 15 ) has a compression hardness at 60% compression of at least 4 kPa as measured according to DIN EN ISO 3386.   
     
     
         29 . The meltblown nonwoven fabric as set forth in  claim 16 ,
 wherein   the annealing temperature is increased in a continuous or stepwise manner during annealing, but on the proviso that the annealing temperature be always at least 0.1° C. below the current melting temperature of the filaments of the meltblown nonwoven fabric existing at this point in time.   
     
     
         30 . A method for manufacturing an annealed meltblown nonwoven fabric having a weight per unit area of from 100 to 600 g/m 2  and having a density of from 5 to 50 kg/m 3 , comprising the following steps:
 a) manufacturing a meltblown nonwoven fabric ( 15 ) and   b) annealing at least a portion of the meltblown nonwoven fabric prepared in step a) at a temperature between the glass transition temperature and 0.1° C. below the melting temperature of the filaments of the meltblown nonwoven fabric.