Oil Filters Containing Strong Base and Methods of Their Use

Abstract

Novel filter elements for sequestering acids from oil or fuel, the strong base floes that comprise the filter elements, and methods of their preparation and use are disclosed. The filter elements comprise a mechanically linked interlocking fiber matrix interspersed with strong base particle floes wherein the strong base particles constitute at least 30% by weight of the filter element. Certain filter elements may be useful for sequestering acids or neutralized acids in certain oils or fuels, for example, the acids originating in the combustion and lubrication system of an internal combustion engine or those contained in oils in an oil circulation system. Other filter elements may be useful for reducing oxidation of an oil.

1 . A filter element for sequestering acids from oil, fluids, or fuel, comprising:
 a matrix formed of mechanically-interlocking structural fibers and interstitial spaces;   strong base particles within the matrix for sequestering acids from oil or fuel, the strong base particles having an average particle size less than the average cross-section of the interstitial spaces; and   a high molecular weight flocculating agent to retain a strong base particle floc formed within the matrix;   wherein:
 1) the smallest unit dimension of the strong base particle floc formed is greater than the average cross-section of the interstitial spaces; 
 2) the strong base particles are substantially unattached to the mechanically-interlocked fibers and are physically bound within the matrix; 
 3) there is substantially no latex chemically binding the strong base particles to the matrix; and 
 4) the strong base particles constitute at least 30% by weight of the filter element. 
   
     
     
         2 . The filter element of  claim 1 , wherein the flocculating agent has a molecular weight of at least about 100,000. 
     
     
         3 . The filter element of  claim 2 , wherein the flocculating agent has a molecular weight of at least about 1,000,000. 
     
     
         4 . The filter element of  claim 1 , the matrix further comprising at least one second mechanically-interlocking fiber selected from fibrillated structural fibers or structural fiber portions, and fibrillated or non-fibrillated small diameter fibers or small diameter fiber portions; or any combination thereof,
 wherein the total amount of the at least one second fiber is less than about 10% by weight of the total amount of structural fiber present in the filter element.   
     
     
         5 . The filter element of  claim 1 , wherein the average particle size of the strong base particles is less than about 10 microns. 
     
     
         6 . The filter element of  claim 1 , wherein the strong base particles comprise magnesium hydroxide, magnesium oxide, zinc oxide, or a combination thereof. 
     
     
         7 . The filter element of  claim 6 , wherein the strong base particles comprise magnesium oxide. 
     
     
         8 . The filter element of  claim 6 , wherein the strong-base-particle-containing filter medium in the filter element has a total acid sequestration capacity of at least about 13 millimoles of octanoic acid per gram of filter element as measured by the Static Test. 
     
     
         9 . The filter element of  claim 1 , wherein the strong base particles after incorporation into the filter element retain at least 40% of their intrinsic surface area, as measured by Hg intrusion porosimetry. 
     
     
         10 . The filter element of  claim 1 , wherein the structural fibers comprise cellulosic fibers, wood fibers, glass fibers, or synthetic fibers, or a combination thereof. 
     
     
         11 . The filter element of  claim 10 , wherein the synthetic fibers comprises at least one of polyester, polynitrile, and polyolefin fibers, or a combination thereof. 
     
     
         12 . The filter element of  claim 1 , wherein the structural fibers have diameters in the range of about 10 to about 60 microns in diameter. 
     
     
         13 . The filter element of  claim 4 , wherein the small diameter fibers or small diameter portions have diameters in the range of from about 0.05 microns to about 10 microns. 
     
     
         14 . The filter element of  claim 1 , wherein the flocculating agent is present in the filter element at a level of less than about 1.5% by weight of total solids. 
     
     
         15 . The filter element of  claim 1 , wherein the flocculating agent is present in the filter element at a level of less than about 0.5% by weight of total solids. 
     
     
         16 . The filter element of  claim 1 , wherein the flocculating agent comprises a polyacrylamide. 
     
     
         17 . The filter element of  claim 1 , further comprising a micro-particle or nano-particle retention aid. 
     
     
         18 . The filter element of  claim 17 , wherein the micro-particle or nano-particle retention aid comprises at least one of colloidal silica, a smectite clay mineral, and an organic micro-polymer 
     
     
         19 . The filter element of  claim 1 , wherein the strong base contained in the filter element constitutes at least about 40% by weight of the filter element. 
     
     
         20 . The filter element of  claim 1 , wherein the strong base contained in the filter element has a surface area of at least 2000 m 2  as measured by Hg intrusion porosimetry. 
     
     
         21 . The filter element of  claim 1 , wherein the oil to be filtered is a lubricating oil, an engine oil, a transformer oil, a transmission fluid, a hydraulic fluid, a turbine oil, a metal working fluid, or an edible oil. 
     
     
         22 . The filter element of  claim 1 , wherein the fuel comprises a biodiesel fuel. 
     
     
         23 . The filter element of  claim 22 , wherein filtration of the biodiesel fuel through the filter element reduces the total acid number to at least about 0.5 as measured by ASTM method D 664. 
     
     
         24 . The filter element of  claim 1 , further comprising a porous backing sheet material having a dry tensile strength of at least about 5 pounds per inch as ASTM method D828. 
     
     
         25 . A method for preparing a filter element for sequestering acids or neutralized acids in at least one oil, comprising:
 slurrying strong base particles in water, water-miscible solvent, or a combination thereof, adding a high molecular weight flocculating agent to floc the strong base particles;   adding structural fibers, or structural fiber portions, or small diameter fibers, or small diameter fiber portions, or any combination thereof, to the slurry to form a fiber matrix interdispersed with the floc of strong base particles;   contacting the fiber matrix with a backing sheet material;   substantially removing the water, water-miscible solvent, or combination thereof; and   depositing the fiber matrix onto the backing sheet material.   
     
     
         26 . The method of  claim 25 , wherein the strong base particles within the filter element comprise magnesium oxide. 
     
     
         27 . The method of  claim 25 , wherein the filter element porous backing sheet material has a dry tensile strength of at least about 5 pounds per inch as measured using ASTM method D828. 
     
     
         28 . A method for sequestering acids from oil containing acids or neutralized acids originating in the combustion and lubrication system of an internal combustion engine, the method comprising:
 contacting in a lubricating oil circulation system a filter element with a lubricating oil containing acids or neutralized acids, or a mixture thereof, wherein the filter element comprises:
 a matrix formed of mechanically-interlocking structural fibers and interstitial spaces; 
 strong base particles within the matrix for sequestering acids from the oil, the strong base particles having an average particle size less than the average cross-section of the interstitial spaces; and 
 a high molecular weight flocculating agent to retain the strong base particle floc formed within the matrix; 
 wherein:
 1) the smallest unit dimension of the strong base particle floc formed is greater than the average cross-section of the interstitial spaces; 
 2) the strong base particles are substantially unattached to the mechanically-interlocked fibers and are physically bound within the matrix; 
 3) there is substantially no latex chemically binding the base particles to the matrix; and 
 4) the strong base constitutes at least 30% by weight of the filter element; 
 
   the filter element causing at least a portion of the acids to remain with the strong base particles within the filter element; and   wherein the strong-base-containing filter element has a total surface area, as measured by Hg intrusion porosimetry, of at least 10 m 2 /gram.   
     
     
         29 . The method of  claim 28 , wherein the strong base particles within the filter element comprise magnesium oxide. 
     
     
         30 . The method of  claim 28 , wherein the filter element further comprises a porous backing sheet material having a dry tensile strength of at least about 5 pounds per inch as measured ASTM method D828. 
     
     
         31 . A method for sequestering acid from oil containing acids or neutralized acids in an oil circulation system, comprising:
 contacting oil in the oil circulation system with a filter element; wherein the filter element comprises:
 a matrix formed of mechanically-interlocking structural fibers and interstitial spaces; 
 strong base particles within the matrix for sequestering acids from the oil, the strong base particles having an average particle size less than the average cross-section of the interstitial spaces; and 
 a high molecular weight flocculating agent to retain the strong base particle floc formed within the matrix; 
 wherein:
 1) the smallest unit dimension of the strong base particle floc formed is greater than the average cross-section of the interstitial spaces; 
 2) the strong base particles are substantially unattached to the mechanically-interlocked fibers and are physically bound within the matrix; 
 3) there is substantially no latex chemically binding the base particles to the matrix; and 
 4) the strong base constitutes at least 30% by weight of the filter element; 
 
   the filter element causing at least a portion of the acids to remain with the strong base particles within the filter element; and
 wherein the strong-base-containing filter element has a total surface area, as measured by Hg intrusion porosimetry, of at least 10 m 2 /gram. 
   
     
     
         32 . The method of  claim 31 , wherein the strong base particles within the filter element comprise magnesium oxide. 
     
     
         33 . The method of  claim 31 , wherein the filter element further comprises a porous backing sheet material having a dry tensile strength of at least about 5 pounds per inch as measured ASTM method D828. 
     
     
         34 . A method of reducing oxidation of an oil, comprising:
 contacting the oil with a filter element to sequester acids at a rate such that oxidation of the oil is decreased by at least about 20% relative to the rate of oxidation in an oil in contact with a non-base containing filter element;   wherein the filter element comprises:
 a matrix formed of mechanically-interlocking structural fibers and interstitial spaces; 
 strong base particles within the matrix for sequestering acids from the oil, the strong base particles having an average particle size less than the average cross-section of the interstitial spaces; and 
 a high molecular weight flocculating agent to retain the strong base particle floc formed within the matrix; 
 wherein:
 1) the smallest unit dimension of the strong base particle floc formed is greater than the average cross-section of the interstitial spaces; 
 2) the strong base particles are substantially unattached to the mechanically-interlocked fibers and are physically bound within the matrix; 
 3) there is substantially no latex chemically binding the base particles to the matrix; and 
 4) the strong base constitutes at least 30% by weight of the filter element; 
 
   the filter element causing at least a portion of the acids to remain with the strong base particles within the filter element; and
 wherein the strong-base-containing filter element has a total surface area, as measured by Hg intrusion porosimetry, of at least 10 m 2 /gram. 
   
     
     
         35 . The method of  claim 34 , wherein the strong base particles within the filter element comprise magnesium oxide. 
     
     
         36 . The method of  claim 35 , wherein the filter element further comprises a porous backing sheet material having a dry tensile strength of at least about 5 pounds per inch as measured ASTM method D828. 
     
     
         37 . A strong base floc, for use in a filter media, comprising:
 strong base particles containing magnesium oxide or zinc oxide or combination thereof and having an average particle size of about 0. 1 to about 10 microns; and   a high molecular weight flocculating agent;   wherein:
 the floc formed from contacting of the flocculating agent and the strong base particles has an average cross-section distance of greater than about 10 microns; 
 the flocced strong base particles retain at least about 40% of their intrinsic surface area as measured by Hg intrusion porosimetry. 
   
     
     
         38 . The flocced strong base particles of  claim 37 , wherein said flocs retain at least about 60% of their intrinsic surface area as measured by Hg intrusion porosimetry. 
     
     
         39 . The strong base floc of  claim 37 , wherein the strong base particles comprise magnesium carbonate, magnesium hydroxide, magnesium oxide, zinc oxide, or a combination thereof. 
     
     
         40 . The strong base floc of  claim 39 , wherein the strong base particles comprise magnesium oxide. 
     
     
         41 . The strong base floc of  claim 37 , wherein the high molecular weight flocculating agent is a polyacrylamide. 
     
     
         42 . The strong base floc of  claim 37 , wherein the high molecular weight flocculating agent is a polyethylene oxide. 
     
     
         43 . The strong base floc of  claim 37 , wherein the high molecular weight flocculating agent has a concentration of less than about 1.5% by weight of the strong base particles in the floc. 
     
     
         44 . The strong base floc of  claim 37 , further comprising a micro-particle retention aid. 
     
     
         45 . The strong base floc of  claim 44 , wherein the micro-particle retention aid comprises at least one of colloidal silica, a smectite clay mineral, and an organic micro-polymer.