Fuel water separation filter medium for removing water from water-hydrocarbon emulsions having improved efficiency

Abstract

A fuel water separation medium for removing water from water-hydrocarbon emulsions is provided, wherein the fuel water separation medium comprises (A) a first layer comprising nanofibers, and (B) a second layer comprising a fibrous web wherein the fibrous web comprises cellulosic fibers.

1 . A fuel water separation medium for removing water from water-hydrocarbon emulsions comprising
 (A) a first layer comprising nanofibers,   (B) a second layer comprising a fibrous web, wherein the fibrous web comprises cellulosic fibers;   wherein the nanofibers have an average fiber diameter of about 50-350 nm, such as about 100-300 nm;   wherein the fuel water separation medium has a basis weight of about 100-300 g/m 2 , such as about 150-300 g/m 2 ;   wherein the fuel water separation medium is characterized by having a net change in water removal efficiency measured according to SAEJ1488 being preferably less than about 10%, more preferably less than about 5 and   wherein the net change in water removal efficiency is defined as follows:
   net change in water removal efficiency=water removal efficiency after 165 min−water removal efficiency after 15 min.
 
   
     
     
         2 . The filter medium according to  claim 1 , wherein the filter medium is characterized by a TSI aerosol penetration of less than or equal to about 15%, preferably less than or equal to about 10%, more preferably less than or equal to about 5%. 
     
     
         3 . The filter medium according to any one of  claim 1  or  2 , wherein the filter medium is characterized by a mean flow pore size of about 2-10 microns. 
     
     
         4 . The medium according to any of the preceding claims, wherein the fibrous web of the second layer is a wet-laid fibrous web. 
     
     
         5 . The medium according to any of the preceding claims, wherein the nanofibers are synthetic nanofibers selected from polyethersulfone (PES); polyacrylonitrile; polyamide (PA) such as nylon; and fluoropolymer such as polyvinylfluoride (PVDF); and/or mixtures thereof. 
     
     
         6 . The medium according to  claim 5 , wherein the nanofibers are polyamide nanofibers or fluoropolymeric nanofibers. 
     
     
         7 . The medium according to any of the preceding claims, wherein the second layer has a basis weight of about 60-250 g/m 2 . 
     
     
         8 . The medium according to any of the preceding claims, wherein the second layer has a Gurley stiffness of about 2-15 g. 
     
     
         9 . The medium according to any of the preceding claims, wherein the second layer comprises substantially no glass fibers. 
     
     
         10 . The medium according to any of the preceding claims, wherein the second layer comprises substantially no synthetic fibers. 
     
     
         11 . The medium according to any of the preceding claims, wherein the second layer comprises cellulosic fibers in an amount of at least about 50% by weight such as at least about 60% by weight or at least about 80% by weight, based on the total weight of second layer. 
     
     
         12 . The medium according to any of the preceding claims, wherein the nanofibers of the first layer, which are preferably prepared from an adhesive, which is preferably used in an amount of about 1 to about 5% by weight, and a polyethersulfone which is preferably used in an amount of about 95 to about 99% by weight, based on the total weight of the nanofibers, are electrospun directly onto the second layer. 
     
     
         13 . The medium according to any of the preceding claims, wherein the first layer consists essentially of nanofibers. 
     
     
         14 . The medium according to any of the preceding claims, wherein the second layer includes substantially no fibrillated fibers such as fibrillated cellulosic fibers. 
     
     
         15 . The medium according to any of the preceding claims, wherein the second layer does not comprise a water repellant additive. 
     
     
         16 . The medium according to any of the preceding claims, wherein the second layer is on a downstream side of the first layer. 
     
     
         17 . The medium according to any one of  claims 1 - 15 , wherein the second layer is on an upstream side of the first layer. 
     
     
         18 . The medium according to any of the preceding claims, wherein the medium does not include a protective fine fiber layer as third layer on an upstream side of the first layer. 
     
     
         19 . The medium according to any one of  claims 1 - 17 , wherein the medium comprises a third layer on an upstream side of the first layer, the third layer being a protective fine fiber layer. 
     
     
         20 . The medium according to any one of  claim 18  or  19 , wherein the protective fine fiber layer comprises, or consists of, synthetic fibers such as synthetic fibers selected from polyester, polyethylene terephthalate, polyolefin, polybutylene terephthalate and/or polyamide. 
     
     
         21 . The medium according to  claims 18 - 20 , wherein the third layer comprises a spunbond fiber sub-layer, such as a PET layer having preferably a basis weight of about 8 to about 30 g/m 2 , and a meltblown fiber sub-layer, such as a PET layer having preferably a basis weight of about 25 to about 80 g/m 2 . 
     
     
         22 . The medium according to  claims 18 - 21 , wherein the third layer has a basis weight of about 10 to about 200 g/m 2  such as about 15 to about 100 g/m 2 . 
     
     
         23 . The medium according to any of  claims 19 - 22 , wherein the second layer is on a downstream side of the first layer and the third layer is on an upstream side of the first layer. 
     
     
         24 . The medium according to any of  claims 19 - 22 , the second layer is on an upstream side of the first layer and the third layer is on an upstream side of the second layer. 
     
     
         25 . The medium according to any of the preceding claims, wherein the medium comprises an adhesive layer between the first and the second layer. 
     
     
         26 . The medium according to any of  claims 19 - 25 , wherein the medium comprises an adhesive layer between the first and the third layer. 
     
     
         27 . The medium according to any one of  claims 25 - 26 , wherein said adhesive layer(s) comprise(s) an adhesive selected from polyurethane; acrylate; PVA; polyolefin ethylene co-polymer; and/or rubber-based adhesive. 
     
     
         28 . The filter medium according to any of the preceding claims, consisting, or consisting essentially, of
 (A) the first layer;   (B) the second layer;   (C) optionally the third layer;   (D1) optionally the adhesive layer between the first and the second layer; and   (D2) optionally the adhesive layer on a downstream side of the third layer, if present.   
     
     
         29 . The filter medium according to any one of  claims 1 - 27 , consisting, or consisting essentially, of
 (A′) the first layer;   (B′) the second layer;   (C′) optionally two of the third layers;   (D1′) optionally the adhesive layer between the first and the second layer; and   (D2′) optionally the adhesive layer on an upstream surface of the second layer.   
     
     
         30 . The medium according to any of the preceding claims, wherein the filter medium is characterized by a basis weight of about 150-300 g/m 2  when tested according to TAPPI Standard T 410 om-02. 
     
     
         31 . The medium according to any of the preceding claims, wherein the filter medium is characterized by an overall fuel-water separation efficiency of at least about 55% after 15 minutes when tested according to SAEJ1488. 
     
     
         32 . The medium according to any of the preceding claims, wherein the filter medium is characterized by an overall fuel-water separation efficiency of at least about 60% after 165 minutes when tested according to SAEJ1488. 
     
     
         33 . The medium according to any of the preceding claims, wherein the filter medium is characterized by a TSI resistance to flow of about 5-75 mm H 2 O. 
     
     
         34 . The medium according to any of the preceding claims, wherein the filter medium is characterized by an air permeability of about 3-20 cfm when tested according to TAPPI Standard T 251 cm-85. 
     
     
         35 . The medium according to any of the preceding claims, wherein the filter medium is characterized by a leakage-corrected Frazier of 3-20 cfm when tested according to TAPPI Standard T 251 cm-85. 
     
     
         36 . Process for the preparation of the medium according to any of  claims 1  to  35 , the process comprising the steps of
 providing a first homogeneous slurry; 
 supplying the first slurry onto a dewatering screen to form a first deposit; 
 removing the water from the deposit to form a wet fibrous web; (d) drying the wet fibrous web while heating to form the second layer; 
 optionally saturating the thus obtained second layer with a binder resin; 
 optionally coating of a first adhesive layer on top of the thus obtained second layer; 
 applying the first layer on top of the second layer or on top of the first adhesive layer coated onto the second layer, wherein the applying is preferably performed using electrospinning; 
 optionally coating of a second adhesive layer (i) on top of the first layer or (ii) on top of the second layer; and 
 optionally applying the third layer (iii) on top of the first layer, (iv) on top of the second adhesive layer coated onto the first layer, if present, (v) on top of the second layer or (vi) on top of the second adhesive layer coated onto the second layer, if present; 
 
       wherein the first slurry comprises water and cellulosic fibers. 
     
     
         37 . Process of  claim 36 , wherein the applying is performed by meltblowing a first fine fiber layer and spunbonding a second fine fiber layer on top of the first fine fiber layer. 
     
     
         38 . A fuel water separation filter medium for removing water from water-hydrocarbon emulsions which is obtainable by the process according to  claim 36  or  37 . 
     
     
         39 . A fuel water separator for removing water from water-hydrocarbon emulsions comprising the medium according to any of  claims 1  to  35  and  38 . 
     
     
         40 . The fuel water separator according to  claim 39 , wherein the filter medium is pleated. 
     
     
         41 . The fuel water separator according to any one of  claims 39 - 40 , wherein the filter medium is corrugated. 
     
     
         42 . The fuel water separator according to any one of  claims 39 - 41 , wherein the filter medium includes a wire mesh supporting layer co-pleated with the filter medium. 
     
     
         43 . The fuel water separator according to any one of  claims 39 - 41 , wherein the filter medium does not include a wire mesh supporting layer co-pleated with the filter medium. 
     
     
         44 . Use of the medium according to any of  claims 1  to  35  and  38  or of the fuel water separator according to  claims 39 - 43  for separating water from water-hydrocarbon emulsions.