Hydroentangled microfibre material and method for its manufacture

Abstract

A method for manufacturing a microfibre material comprises forming a fibre web containing microfibres and, thereafter, subjecting the fibre web to hydraulic entanglement. At least a majority of the microfibres have been stretched to orientation and have shell surfaces substantially completely covered by a hydrophilic lubricating layer. The method further comprises dispersing the microfibres in an aqueous medium before forming by interacting the hydrophilic lubricating layer with the aqueous medium to form a substantially homogenous fibre dispersion, wherein the microfibres in a straightened condition have a fibre thickness smaller than 0.5 denier and a fibre length larger than 5 mm both in the fibre dispersion and in the microfibre material. In the microfibre material a majority of the microfibres are stretched to orientation, exhibit a cross-sectional shape which substantially can be described by an arc or several successive arcs, and are uniformly distributed in a x,y-plane of the microfibre material.

1 . A method for manufacturing a microfibre material, which comprises: 
 providing at least a majority of microfibres having been stretched to orientation and having shell surfaces substantially completely covered by a hydrophilic lubricating layer;    dispersing said microfibres in an aqueous medium by interacting said hydrophilic lubricating layer with said aqueous medium in order to form a substantially homogenous fibre dispersion;    forming a fibre web containing said microfibres; and    subjecting said fibre web to hydraulic entanglement in order to obtain said microfibre material;    wherein said microfibres in a straightened condition have a fibre thickness small than 0.5 denier and a fibre length larger than 5 mm both in said fibre dispersion and in said microfibre material.    
     
     
         2 . The method according to  claim 1 , wherein said aqueous medium is constituted primarily of water, and said microfibres have a fibre length which is between 5 and 10 mm.  
     
     
         3 . The method according to  claim 1 , wherein said aqueous medium is constituted primarily of a foam, and said microfibres have a fibre length which is between 10 and 25 mm.  
     
     
         4 . The method according to  claim 1 , wherein a proportion of pulp fibres is also dispersed in said aqueous medium together with said microfibres.  
     
     
         5 . The method according to  claim 1 , wherein, counted on a total quantity of dry fibres, 10-100 weight-% of said microfibres and 0-90 weight-% of pulp fibres are dispersed in said aqueous medium.  
     
     
         6 . The method according to  claim 1 , wherein said hydrophilic lubricating layer is applied as a spin finish before short-cutting said microfibres.  
     
     
         7 . The method according to  claim 1 , wherein less than 300 kWh/ton of entangling power is consumed in said hydraulic entanglement.  
     
     
         8 . The method according to  claim 1 , wherein a hydraulic pressure no greater than 120 bar is used in said hydraulic entanglement.  
     
     
         9 . The method according to  claim 1 , the microfibre material is subjected to a corona or plasma treatment after said hydraulic entanglement in order to modify a possible residue of said hydrophilic lubricating layer to provide an increased fibre-fibre friction.  
     
     
         10 . A microfibre material manufactured by means of hydraulic entanglement, 
 said microfibre material including microfibres which in a straightened condition have a fibre thickness smaller than 0.5 denier and a fibre length larger than 5 mm, and wherein at least a majority of said microfibres have been stretched to orientation, exhibit a cross-sectional shape which substantially can be described by an arc or several successive arcs, and are uniformly distributed in a x-y-plane of said microfibre material.    
     
     
         11 . The microfibre material according to  claim 10 , wherein substantially all shell surfaces of said majority of microfibres exhibit an equivalent micro-surface roughness.  
     
     
         12 . The microfibre material according to  claim 10 , wherein substantially all neighbouring microfibres, of said majority of microfibres, exhibit different extensions in said x,y-plane.  
     
     
         13 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a formation created by wetforming, and said majority of microfibres have a fibre length between 5 and 10 mm.  
     
     
         14 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a formation created by foamforming, and said majority of microfibres have a fibre length between 10 and 25 mm.  
     
     
         15 . The microfibre material according to  claim 10 , wherein the microfibre material includes a proportion of pulp fibres together with said microfibres.  
     
     
         16 . The microfibre material according to  claim 10 , wherein the microfibre material, counted on a total quantity of dry fibres, includes 10-100 weight-% of said microfibres and 0-90 weight-% of pulp fibres.  
     
     
         17 . The microfibre material according to  claim 10 , wherein certain shell surfaces of said microfibres exhibit a residue of a hydrophilic lubricating agent.  
     
     
         18 . The microfibre material according to  claim 10 , wherein certain shell surfaces of said microfibres exhibit an oxidized residue of a hydrophilic lubricating agent.  
     
     
         19 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a tensile index {square root} MD*CD which is larger than 20 Nm/g both in a dry state and in water.  
     
     
         20 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a tensile index {square root} MD*CD which is larger than 15 Nm/g in a lubricating, hydrogen bond-dissolving surfactant solution.  
     
     
         21 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in water within the pore radius interval 5-250 μm, having a volume maximum at a pore radius smaller than 15 μm.  
     
     
         22 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in hexadecane within the pore radius interval 5-250 μm, having a volume maximum at a pore radius smaller than 15 μm.  
     
     
         23 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in water, having a cumulative pore volume which is at least 30% of the total pore volume of the microfibre material for pore radii between 5 and 20 μm and at least 90% of said total pore volume for pore radii between 5 and 60 μm.  
     
     
         24 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in hexadecane, having a cumulative pore volume which is at least 25% of the total pore volume of the microfibre material for pore radii between 5 and 20 μm and at least 70% of said total pore volume for pore radii between 5 and 60 μm.  
     
     
         25 . A microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in water, in which less than 20% of the total pore volume of the microfibre material is located in pores having a pore radius exceeding 40 μm.  
     
     
         26 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD in hexadecane, in which less than 20% of the total pore volume of the microfibre material is located in pores having a pore radius exceeding 70 μm.  
     
     
         27 . The microfibre material according to  claim 10 , wherein the microfibre material exhibits a pore size distribution, measured by PVD, in which less than 2.5% of the total pore volume of the micro fibre material, both when measured in water and in hexadecane, is located in pores having a pore radius exceeding 150 μm.