Method of making a spun-bonded nonwoven for packaging

Abstract

A package has walls formed of a weldable spun-bonded nonwoven and having welded wall regions. The spun-bonded nonwoven has continuous filaments of a thermoplastic plastic each with a thermoplastic core surrounded by a thermoplastic sheath. The sheaths of the continuous multicomponent filaments of both components contain at least 3 wt % of at least one filler so that weldability of the spun-bonded nonwoven is improved by reducing a welding temperature in thermal welding of the spun-bonded nonwoven. A first plastic component forming the sheaths of the multicomponent filaments has the same or a lower melting point than a second plastic component forming the cores of the filaments.

1 . A method of making a weldable spun-bonded nonwoven or packaging spun-bonded nonwoven comprising the steps of:
 spinning endless filaments having sheaths of a first thermoplastic surrounding respective cores of a second thermoplastic wherein   the sheaths contain at least 3 wt % of at least one filler,   the first thermoplastic forming the sheaths of the multicomponent filaments has the same or a lower melting point than the second thermoplastic forming the cores of the filaments such that filaments are weldable to each other by fusing together the sheaths,   a mass ratio of the first plastic component forming the sheaths to the second plastic component forming the cores is 25:75 to 50:50 and in welded regions 35:65 to 50:50;   depositing the filaments to form a spun-bonded nonwoven web;   calendering an outer face of the spun-bonded nonwoven web smooth and without engraving; and   engraving an inner face of the spun-bonded nonwoven web 15 to 35% and to an embossing depth of 0.1 to 0.6 mm.   
     
     
         2 . The method according to  claim 1 , wherein the first plastic of the continuous filaments has 4 to 25 wt % of the filler. 
     
     
         3 . The method according to  claim 1 , wherein the filler is a metal salt. 
     
     
         4 . The method according to  claim 1 , further comprising after the step of spinning and before the step of depositing the steps of sequentially:
 cooling the filaments in a cooler; and   stretching the cooled filaments in a stretcher.   
     
     
         5 . The method according to  claim 1 , wherein during calendering the spun-bonded nonwoven is pressed with a calender having an embossing surface of 10 to 90% to 30%. 
     
     
         6 . The method according to  claim 1 , wherein a number of engraved points of the calender is greater than 30/cm 2 . 
     
     
         7 . The method according to  claim 1 , wherein the first component of the continuous filaments has 4 to 25 wt % of the filler. 
     
     
         8 . The method according to  claim 1 , wherein the melting point of the second plastic of the cores is above that of first thermoplastic of the sheaths, the method further comprising the steps after engraving of:
 cutting pieces of the web, and   welding the pieces together at edges thereof by applying sufficient heat to melt only the sheaths of the filaments, whereby the melted sheets fuse together.   
     
     
         9 . A package having walls formed of a weldable spun-bonded nonwoven and having welded wall regions, wherein
 the spun-bonded nonwoven has continuous multicomponent filaments of a thermoplastic plastic of both components each have a thermoplastic core surrounded by a thermoplastic sheath,   the sheaths of the continuous multicomponent filaments of both components contain at least 3 wt % of at least one filler, whereby weldability of the spun-bonded nonwoven is improved by reducing a welding temperature in thermal welding of the spun-bonded nonwoven,   a first plastic component forming the sheaths of the multicomponent filaments has the same or a lower melting point than a second plastic component forming the cores of the filaments,   a mass ratio of the first plastic component forming the sheaths to the second plastic component forming the cores is 25:75 to 50:50 and in the welded wall regions 35:65 to 50:50,   an outer face of the spun-bonded nonwoven is calendered smooth and without engraving, and   an inner face of the spun-bonded nonwoven is engraved 15 to 35% and to an embossing depth of 0.1 to 0.6 mm.   
     
     
         10 . The package according to  claim 9 , wherein the first component of the continuous filaments has 4 to 25 wt % of the filler. 
     
     
         13 . The package according to  claim 9 , wherein the filler is a metal salt. 
     
     
         14 . The package according to  claim 9 , wherein the package is formed of a plurality of pieces of the calendered and engraved nonwoven joined together at seams where the first thermoplastic of the sheaths are fused together but the second thermoplastic of the cores is not fused.