Triple head draw slot for producing pulp and spunmelt fibers containing web

Abstract

The present invention is a novel improved process and apparatus for making polymeric fibers and combining these with cellulosic fibers so as to form a fibrous-containing nonwoven, and in particular fibrous material containing spunmelt nonwoven.

1 . A method for forming a fiber containing web,
 said fiber containing web comprising
 spunmelt fibers; 
 fibrous material, preferably cellulosic pulp material; 
   said method comprising the steps of   (i) providing
 a supply unit for polymeric material; 
 a supply unit of fibrous material; 
 a filament forming unit comprising a melt-extruder for said polymeric material and a die head; 
 a fibrous material delivery unit; 
 a drawing unit comprising a filament infeed; at least one, preferably two fibrous material infeed(s.); a drawing channel; and a drawing channel outlet; 
 a collection unit; 
 means for creating air flows at predetermined flow rates for air with predetermined temperatures; and 
   (ii) forming filaments of polymeric material in said filament forming unit;   (iii) transferring said formed filaments to said a filament entry slot of said drawing unit, thereby quenching and drawing said filaments by a first air flow,   wherein said process further comprises the steps of   (iv) suspending said fibrous material in an additional air flow and transferring said fibrous material in said air flow to said fibrous material infeed(s) of said drawing unit   whereby said fibrous material infeed(s) is/are separate from said filament infeed;   (v) feeding said filaments and said fibrous material into said drawing channel;   (vi) creating an air flow in said drawing channel thereby mixing said fibrous material and said filaments, and   (vii) collecting said mixed spunmelt fibers and fibrous material on a collection unit, thereby forming said fiber containing web.   
     
     
         2 . A method according to  claim 1 , wherein one or more of the conditions selected from the group consisting of the following, are satisfied:
 a1) said polymeric material for forming the filaments is an olefinic polymeric material,   a2) said polymeric material for forming the filaments is an olefinic polymeric material of the polypropylene type,   a3) said polymeric material for forming the filaments is an olefinic polymeric material of the polypropylene type exhibiting a MFI of between 15 and 70 g/10 min, when determined according to ASTM 1237-(4) (230° C./2.16 kg);   b) said fibrous material is cellulosic pulp material;   c1) said fibrous material comprises particulate material,   c2) said fibrous material comprises superabsorbent polymer particles as particulate material;   d) said spunmelt fibers exhibit a diameter of between 10 μm and 40 μm;   e1) said spunmelt fibers exhibit a length of more than 20 mm,   e2) said spunmelt fibers exhibit a length of more than 40 mm,   e3) said spunmelt fibers exhibit a length of less than 250 mm,   e4) said spunmelt fibers exhibit a length of less than 150 mm;   f) said additional air flow is at a temperature of between 32° C. and 35° C., when being added to said fibrous material;   g) said additional air flow is at a relative humidity of less than 85%, when being added to said fibrous material;   h1) said additional air flow is provided at a ratio of from 10 Nm 3  to 50 Nm 3  of air relative to 1 kg of fibrous material, on an hourly basis and per meter length of drawing unit;   h2) said additional air flow is provided at a ratio of from 20 Nm 3  to 30 Nm 3  of air relative to 1 kg of fibrous material, on an hourly basis and per meter length of drawing unit;   h3) said additional air flow is provided at a ratio of about 25 Nm 3  of air relative to 1 kg of fibrous material, on an hourly basis and per meter length of drawing unit;   j) said creation of an airflow in said drawing channel in step (vi) creates a Venturi effect of pulling further air through said filament infeed; and   k) said filaments are broken into meltblown fibers at a predetermined fiber length distribution.   
     
     
         3 . An apparatus for making a fiber-containing web, said apparatus comprising
 means for providing meltable polymeric material;   a filament forming unit comprising a melt-extruder for said polymeric material and a die head for forming filaments;   means for creating air flow; and   means for providing and delivering fibrous material;   a drawing unit positioned below said filament forming unit, adapted to receive said filaments and said fibrous material, and comprising
 a filament entry slot opening adapted to receive said filaments: 
 an exit slot downwardly opposite of said filament entry slot; 
 a drawing channel positioned there between; 
   a means for collecting fibers thereby forming said fiber containing web;   said apparatus being characterized in that   said drawing unit further comprises at least one, two fibrous material infeed separate from said filament entry slot and adapted to deliver said fibrous material suspended in an air flow to said drawing channel,   and wherein said drawing channel is adapted to mixing of said spunmelt filaments and said fibrous material and optionally create breaking of the filament into meltblown fibers.   
     
     
         4 . An apparatus for making a fiber-containing web according to  claim 3 , wherein further the width of the air flow infeed at the point of connection to said drawing channel is less than about 0.8 mm. 
     
     
         5 . An apparatus for making a fiber-containing web according to  claim 3 , wherein said exit slot of said drawing channel exhibits an exit gap width of less than about 15 mm. 
     
     
         6 . An apparatus for making a fiber-containing web according to  claim 5 , wherein the ratio of said exit gap width to said width of the air flow infeed at the point of connection to said drawing channel is less than about 20. 
     
     
         7 . An apparatus for making a fiber containing web according to  claim 3 , wherein said drawing channel comprises a first and a diffusor portion and said fibrous material infeed is adapted to deliver said fibrous material to said diffusor portion of said drawing channel, 
     
     
         8 . An apparatus for making a fiber containing web according to  claim 7 , further comprising an air gap adapted to deliver additional process air at the transition region from said first drawing channel portion to said diffusor portion. 
     
     
         9 . A method for the reduction of energy consumption of an apparatus for forming a fiber containing web according to  claim 4  said method comprising the steps on concurrently reducing the width of the air flow infeed at the point of connection to said drawing channel and the width of the exit gap width. 
     
     
         10 . An apparatus for making a fiber-containing web according to  claim 4 , wherein further the width of the air flow infeed at the point of connection to said drawing channel is less than about 0.65 mm. 
     
     
         11 . An apparatus for making a fiber-containing web according to  claim 10 , wherein further the width of the air flow infeed at the point of connection to said drawing channel is less than about 0.4 mm. 
     
     
         12 . An apparatus for making a fiber-containing web according to  claim 5 , wherein said exit slot of said drawing channel exhibits an exit gap width of less than about 15 mm. 
     
     
         13 . An apparatus for making a fiber-containing web according to  claim 12 , wherein said exit slot of said drawing channel exhibits an exit gap width of less than about 12 mm. 
     
     
         14 . An apparatus for making a fiber-containing web according to  claim 13 , wherein said exit slot of said drawing channel exhibits an exit gap width of less than about 8 mm. 
     
     
         15 . An apparatus for making a fiber-containing web according to  claim 14 , wherein said exit slot of said drawing channel exhibits an exit gap width of less than about 5 mm. 
     
     
         16 . An apparatus for making a fiber-containing web according to  claim 6 , wherein the ratio of said exit gap width to said width of the air flow infeed at the point of connection to said drawing channel is less than about 18.5. 
     
     
         17 . An apparatus for making a fiber-containing web according to  claim 13 , wherein the ratio of said exit gap width to said width of the air flow infeed at the point of connection to said drawing channel is less than about 15.5. 
     
     
         18 . An apparatus for making a fiber-containing web according to  claim 14 , wherein the ratio of said exit gap width to said width of the air flow infeed at the point of connection to said drawing channel is less than about 10.