Pleated Filter Material for Smoking Articles

Abstract

A filter material for manufacturing a segment of a smoking article is described, wherein the filter material comprises a hydro-entangled nonwoven and the nonwoven comprises fibers, wherein the fibers are selected from the group consisting of pulp fibers, fibers of regenerated cellulose and mixtures thereof, and these fibers are together contained in the nonwoven in an amount of at least 50% and at most 100% of the mass of the hydro-entangled nonwoven, and wherein the nonwoven is in the form of a web, has a longitudinal direction in the running direction of the web, a cross direction orthogonal thereto and lying in the plane of the web and a thickness direction orthogonal to longitudinal direction and the cross direction. The nonwoven is shaped such that it has a wave structure in the plane formed by the cross direction and the thickness direction with a wave height of at least 50 µm and at most 1000 µm, as well as a wave length ( 22 , 32 , 42 ) of at least 150 µm and at most 5000 µm.

1 . A filter material for manufacturing a segment of a smoking article, wherein the filter material comprises a hydro-entangled nonwoven and the nonwoven comprises fibers, wherein the fibers are selected from the group consisting of pulp fibers, fibers of regenerated cellulose and mixtures thereof, and these fibers are together contained in the nonwoven in an amount of at least 50% and at most 100% of the mass of the hydro-entangled nonwoven, and wherein the nonwoven is in the form of a web, has a longitudinal direction in the running direction of the web, a cross direction orthogonal thereto and lying in the plane of the web and a thickness direction orthogonal to longitudinal direction and the cross direction and is shaped such that the nonwoven has a wave structure in the plane formed by the cross direction and the thickness direction with a wave height of at least 50 µm and at most 1000 µm, as well as a wave length of at least 150 µm and at most 5000 µm. 
     
     
         2 . The filter material as claimed in  claim 1 , in which the wave height is at least 150 µm and at most 800 µm. 
     
     
         3 . The filter material as claimed in  claim 1 , in which the wave length is at least 500 µm and at most 2000 µm. 
     
     
         4 . The filter material as claimed in  claim 1 , in which the amount of pulp fibers, of fibers of regenerated cellulose or of said mixture thereof is at least 60% and at most 95%, each with respect to the mass of the hydro-entangled nonwoven. 
     
     
         5 . The filter material as claimed in  claim 1 , in which the pulp fibers are sourced from coniferous woods, spruce, pine or fir, deciduous woods, hemp, flax, jute, ramie, kenaf, kapok, coconut, abacá, sisal, cotton or esparto grass or are formed by a mixture of two or more different pulp fibers from these origins. 
     
     
         6 - 7 . (canceled) 
     
     
         8 . The filter material as claimed in  claim 1 , in which the hydro-entangled nonwoven consists substantially exclusively, but at least to 95% with respect to the mass of the hydro-entangled nonwoven of pulp fibers, fibers of regenerated cellulose or a mixture thereof. 
     
     
         9 . The filter material as claimed in  claim 1 , in which the hydro-entangled nonwoven of the filter material contains at least 5% and less than 50% staple fibers from cellulose acetate, each with respect to the mass of the hydro-entangled nonwoven. 
     
     
         10 . The filter material as claimed in  claim 1 , in which the basis weight of the hydro-entangled nonwoven is at least 25 g/m 2  and at most 150 g/m 2  . 
     
     
         11 . The filter material as claimed in  claim 1 , in which the thickness of the hydro-entangled nonwoven is at least 120 µm and at most 800 µm . 
     
     
         12 . The filter material as claimed in  claim 1 , in which the density of the hydro-entangled nonwoven is at least 80 kg/m 3  and at most 220 kg/m 3 . 
     
     
         13 . The filter material as claimed in  claim 1 , in which the width-related tensile strength of the hydro-entangled nonwoven is at least 0.07 kN/m and at most 4 kN/m. 
     
     
         14 - 16 . (canceled) 
     
     
         17 . A segment comprising a filter material as claimed in  claim 1  and a wrapper material. 
     
     
         18 . (canceled) 
     
     
         19 . The segment as claimed in  claim 17 , with a length of at least 6 mm and at most 35 mm. 
     
     
         20 . The segment as claimed in  claim 17 , with a draw resistance in accordance with ISO 6565:2015 of at least 1 mmWG/mm and at most 12 mmWG/mm. 
     
     
         21 - 23 . (canceled) 
     
     
         24 . A smoking article comprising a segment that contains an aerosol-forming material and a segment as claimed in  claim 17 . 
     
     
         25 . The smoking article as claimed in  claim 24 , wherein the smoking article is a filter cigarette and the aerosol-forming material is formed by tobacco. 
     
     
         26 . The smoking article as claimed in  claim 24 , during the intended use of which the aerosol-forming material is just heated but not burnt. 
     
     
         27 . A process for manufacturing a filter material for smoking articles comprising the following steps A to D,
 A - providing a fiber web comprising fibers, selected from the group consisting of pulp fibers, fibers from regenerated cellulose and mixtures thereof,   B - hydro-entangling the fiber web by means of a plurality of water jets directed onto the fiber web,   C - generating a wave structure in the nonwoven by means of a plurality of water jets directed onto the fiber web, and   D - drying the hydro-entangled nonwoven,   wherein the proportion of said fibers in the fiber web in step A is selected such that these fibers are together contained in an amount of at least 50% and at most 100% of the mass of the hydro-entangled nonwoven in the dried state from step D, wherein the fiber web provided in step A has a longitudinal direction in the running direction of the fiber web, a cross direction orthogonal thereto lying in the plane of the fiber web and a thickness direction orthogonal to longitudinal direction and cross direction, and the water jets directed onto the fiber web in step C are disposed such that they have a distance from each other in cross direction from center point to center point of the water jets at the location of impact on the fiber web of at least 150 µm and at most 5000 µm and the pressure of each water jet in step C is at least 2 MPa and at most 70 MPa, and the nonwoven obtained in step D has a wave structure in the plane formed by the cross direction and the thickness direction with a wave height of at least 50 µm and at most 1000 µm, as well as a wave length of at least 150 µm and at most 5000 µm.   
     
     
         28 . The process as claimed in  claim 27 , in which the water jets for carrying out step C are directed onto both sides of the fiber web. 
     
     
         29 . (canceled) 
     
     
         30 . The process as claimed in  claim 27 , in which the water jets in step C exit from an opening which has an area of at least 450 µm 2  and at most 50000 µm 2  and is a circular opening. 
     
     
         31 . The process as claimed in  claim 27 , in which the pressure of the water jets in step C is at least 3 MPa and at most 40 MPa, wherein the pressure for generating the wave structure is selected as a function of the speed of the fiber web in a manner such that for the ratio p/v of the pressure p in MPa to the speed v of the fiber web in m/s, that the following holds: 2.5 ≤ p/v ≤ 20 . 
     
     
         32 . The process as claimed in  claim 27 , in which the pressure of the water jets in step B is at least 0.5 MPa and at most 60 MPa, wherein the pressure in step B is selected as a function of the speed of the fiber web such that for the ratio p/v of the pressure p in MPa to the speed v of the fiber web in m/s, that the following holds: 2 ≤ p/v ≤ 20. 
     
     
         33 - 35 . (canceled) 
     
     
         36 . The process as claimed in  claim 27 , in which in a variation A1 of the process, the fiber web in step A is provided by means of a wet-laid process, which comprises the following sub-steps A1.1 to A1.3:
 A1.1 - manufacturing an aqueous suspension comprising fibers selected from the group consisting of pulp fibers, fibers from regenerated cellulose and mixtures thereof, in which the amount of fibers is selected such that these fibers are together contained in an amount of at least 50% and at most 100% of the mass of the hydro-entangled nonwoven in the dried state from step D,   A1.2 - applying the suspension from step A1.1 to a running wire, and   A1.3 - de-watering the suspension by means of the running wire in order to form a fiber web, in which the process comprises a further sub-step A1.4:   A1.4 - adjusting the moisture content of the fiber web by drying or moistening, wherein the aqueous suspension in step A1.1 has a solid content of at least 0.01% and at most 0.2%, in which the running wire of steps A1.2 and A1.3 is inclined upwards in the running direction of the fiber web from the horizontal by an angle of at least 5° and at most 30°.   
     
     
         37 - 40 . (canceled) 
     
     
         41 . The process as claimed in  claim 27 , in which in a variation A2 of the process, the fiber web in step A is provided by means of an air-laid process, which comprises the following sub-steps A2.1 and A2.2:
 A2.1 - manufacturing a fiber web by an air-laid process, wherein the fiber web comprises fibers which are selected from the group consisting of pulp fibers, fibers from regenerated cellulose and mixtures thereof, in which the amount of these fibers is selected in a manner such that these fibers are together contained in an amount of at least 50% and at most 100% of the mass of the hydro-entangled nonwoven in the dried state from step D, and   A2.2 - moistening the fiber web.   
     
     
         42 . The process as claimed in  claim 27 , in which the drying in step D is at least partially carried out by through-air drying.