Title of Invention	"IMPROVED FILTER MEDIA AND METHOD OF MANUFACTURE THEREOF"
Abstract	The present invention relates to an improved filter media for manufacture of a filter element and to a method for the manufacture thereof. In particular, the present invention relates to an improved filter media for water separation in diesel filters, diesel filters made using such media and to a method for the manufacture of diesel filters using such media.

Full Text

IMPROVED FILTER MEDIA, FILTER MADE THEREWITH AND METHOD OF MANUFACTURE THEREOF FIELD OF THE INVENTION The present invention relates to an improved filter media and to a filter made therefrom and to a method for the manufacture thereof. In particular, the present invention relates to an improved filter media for water separation in diesel filters, diesel filters made using such media and to a method for the manufacture of diesel filters using such media. BACKGROUND OF THE INVENTION A filter media is a bonded sheet of fibers with mesh type porous structure. The design of a filter paper depends on the specific application and the functional requirements therefor. Generally, different fiber varieties with different morphological characteristics are blended together to obtain a filter media with the desired end use characteristics. The fibers generally used in filter media are either man made or natural and go through various processing steps to obtain filler media with suitable characteristics for the end use. It is important to note that apart from functional properties, specific mechanical properties are also required to enable easy processing of the filter media. Natural fibers have inherent capacity to form hydrogen bonds. However, in order to enhance the mechanical properties of the natural fibers, additives are added either at the wet end during base filter paper manufacturing or at dry end when the paper dries out. Such additives normally comprise chemical reagents that react with the fibers to form bonds that enhance the strength of the paper. Additives are also necessary to enhance the paper smoothness/roughness, appearance, barrier/resistance properties and the like. Base paper in unimpregnated state has low strength. Depending on the filter application, the filter media has to be applied for different mediums such as oil, fuel, and air and the like. Filter papers are porous and have a tendency to be saturated with the medium they are exposed to. The fibers are hygroscopic in nature and swell by absorbing external fluids which causes reduction in porosity and affects the performance. In order to provide strength when the filter is put into an external medium and to avoid swelling of the fibers, the base filter media is impregnated with a resin. This resin saturates the fibers, protects change in permeability, and also provides mechanical strength to the media. Resins are of two types - curable resins and no cure resins. Curable resins require heat to be cured while no cure resins get cured at ambient conditions. After the resin is cured, it is thermally settled with the fibers and cannot be extracted out from the filter paper. Additives are also added to the filter paper during impregnation in order to improve the surface properties of the media. Grooving, pleating and marking are all done to get the final filter properties. Grooving comprises corrugating the filter paper which increases the specific surface area thereby providing more surface area for filtration and as a result increasing the dust holding capacity and the life of the filter. Marking is done in order to distinguish the two sides of the filter media. Generally, it is the out flow side of the paper that is marked. Pleating is done hi order to provide a specific geometry to the paper. Prior art filter media used for fuel filtration comprises 100% natural fibers such as cellulose. Cellulose fibers are blended and formed into a sheet of paper. The optimum grammage of the paper is 250 gm/m2. Conventional additives can be added during formation of the filter media. In the art, the filter paper is impregnated with phenolic resin (phenol-formaldehyde resol) Grade Analak 01. This is a thermally curable resin and gets cured at a temperature of ISO - 160°C in a time period of about 10 minutes. Methanol is used as a solvent for the resin. The solution contains 20 - 22 % of the resin. Since this resin is completely soluble in methanol at room temperature, moderate churning is required to obtain uniform mixing. This blend is applied on the filter paper with the help of a pick up roll. The average weight of the resin applied on the paper is around 20% of the total weight of the impregnated filter paper. The paper is slit into the desired filter height after curing and the filter than manufactured. However, one disadvantage of the prior art filters is that the water separation efficiency is not high. Prior art filters report a water separation efficiency of only about 54 % when tested at ambient temperature and a flow rate of about 160 LPH with a water addition rate of about 2% of the flow rate. It is important to improve the water separation efficiency of the filter media in order to ensure that filter life is prolonged, efficiency is improved and costs for the user reduced. OBJECTS OF THE INVENTION Accordingly, it is an object of the invention to provide a filter with improved water separation efficiency. It is another object of the invention to provide a fuel filter that provides better performance than prior art filters. It is further object of the invention to provide a fuel filter that avoids the problems associated with prior art filter media which uses natural fibers and phenolic resins. It is yet another object of the invention to provide a resin composition that enables improvement in the water separation efficiency of the filter media to which the resin composition is applied. It is yet another object of the invention to provide a filter media which comprises natural and synthetic fibers thereby improving the absorption capacity of the media. SUMMARY OF THE INVENTION Accordingly, the present invention relates to a novel filter media comprising hardwood and softwood fibers blended with about 10% of the total weight of the media of polyester fibers. In one embodiment of the invention, filter media has base weight of about 220 GSM. In another embodiment of the invention, the filter media is impregnated with a no cure resin comprising a mixture of methyl methacrylate and isobutyl methacrylate in an amount of up to 8% of the total weight of the filter media. In yet another embodiment of the invention, conventional wet end additives, such as MF and starches, is incorporated in the filter media. The present invention also comprises a fuel filter comprising a filter element in a predetermined pattern and with two ends opposite each other, end caps being connected to said opposing ends of said filter element, said filter element comprising a filter media impregnated with a resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate in an amount of up to 8% of the total weight of the filter element. In another embodiment of the invention, silicone is added to the resin blend as a cross linking agent in an amount of up to 2% concentration by volume of the resin solution. In one embodiment of the invention, the filter element comprises of filter paper pleated in the form of a zig-zag shape with dimples provided at even distances on the surface thereof so as to create interstitial spaces between succeeding pleats of the filter element. In one embodiment of the invention, the sealing is done by ultrasonic welding. In another embodiment of the invention, the sealing is done by heat welding. In an embodiment of the invention, the end caps comprise Polyamide grade end caps. In another embodiment of the invention, the end caps comprise metal end caps. In a further embodiment of the invention, the sealing layer comprises conventional adhesive. In yet another embodiment of the invention, the paper filter element is joined to the polyamide end caps with hot plate joining technique. In yet another embodiment of the invention, the cutting of the filter felt is carried out by ultrasonic cutting technique. The present invention also relates to a method for the manufacture of a filter media for use in fuel filters said filter media comprising hardwood and softwood fibers blended with about 10% of the total weight of the media of polyester fibers, said method comprising blending a mixture of hardwood and softwood fibers and then blending up to 10 % by weight of the total media of polyester fibers, forming said blend into a roll, impregnating said filter media roll with a no cure resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate dissolved in water, drying said filter media and shaping said dried filter media roll as desired. In another embodiment of the invention, silicone is added to the resin blend as a cross linking agent in an amount of up to 2% concentration by volume of the resin solution. The invention also relates to a novel resin composition comprising a mixture of methyl methacrylate and iso butyl methacrylate, the ratio of the two ingredients being in the range of 1 - 99: 99 -1 by weight. DETAILED DESCRIPTION OF THE INVENTION The filter media of the invention comprises hardwood and softwood fibers blended with about 10% of die total weight of the media of polyester fibers. This results in a filter media with improved dust holding capacity and paniculate efficiency without any sacrifice of mechanical properties and other functional properties. The basis weight is optimized to 220 GSM with optimum thickness in order to obtain optimum performance. Modified polymers of wet end additives such as MF and starches improve the water separation of the filter media. The filter media is impregnated with a novel resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate. The resin composition is water soluble and therefore water is used as a solvent to dissolve the resin before impregnation onto the filter media. The resin composition is also of the no-cure resin type thereby requiring no special heat treatment after impregnation. The resin solution normally comprises 10% of solid (resin) in the solvent. Since the resin is completely soluble in water at room temperature, only moderate churning is required to obtain uniform mixing. The blend can be applied to the filter media through a pick up roll The average weight of the resin applied on the filter media is about 8% of the total weight of the impregnated filter media. After impregnation where the fibers absorb the resin, the solvent water is dried out with hot air blowers. If desired, screen side of the filter media can be provided with indication to indicate the out flow in the filter. Silicone of various grades can be used as a cross linker blended in the acrylic resin composition. A preferred silicone grade is Grade MH '5 of M/s Aerotech Ltd. The cross linking agent when used is in the amount of 1 - 2% of the resin blend by volume. After drying, the resin coated filter media is again coated with a silicone preferably of grade 1185 and then dried with hot air blowers. The silicone fumes that emerge are incinerated in an incinerator. This serves the additional advantage of generating heat for drying of the filter media. The use of silicone enhances the water repellancy of the filter media apart from other surface properties. In another embodiment, use of PVC based adhesives as in the prior art, which results in several disadvantages such as the chances of bypass, is avoided since the filter paper becomes an integral part of the polyamide based end cap and use of polyamide hot melt for sealing the two end layers. This procedure of avoiding metal in the filter end caps also ensures that complicated shapes are easily achieved without a substantial increase in costs. The use of thermoplastic as end cap material also provides several advantages such as the use of less raw material, lower scrap volume and consequential lower environmental burden and reduced waste disposable problem. Other advantages are that the element assemblies are corrosion resistant and do not require separate plating as is required in prior art metal caps. The use of polyamide end caps also ensures that complicated shapes of end discs are easy to make since plastics are easily moldable and are light in weight. It was also postulated that the use of lightweight filters would result in increased engine efficiency. Raw material cost of end discs is less as compared to existing metal cap and adhesive cost. In view of the decision to use polyamides grades which are thermophilic, it was decided that ultrasonic welding and hot plate welding could be tried to join the end pleats and filter elements with the end caps to ensure a permanent seal without loss of performance. It was also observed that the bypass of filter is less as compared to existing filter using metallic components was less because in plastic component design paper is directly embedded in end cap. In existing design, paper is bonded with metal end cap with adhesive. Life of filter increases since paper is embedded less than metal cap collar length so more paper is available for filtration. As more filtration is possible in the same geometry. It is another part of the invention that the pleating design can be varied according to the filter design, desired filter output, the filter material input, customer requirements and other factors. Commonly below mentioned pleating are used in oil/ fuel and air filter application. Cloth type filters for fuel application are also bonded with these techniques. However, different pleating design such as star type pleating whether grooved or dimpled, zig zag pleating, m-type pleating, coil type pleating, can be accommodated with these techniques. There are several advantages in cross dimpling of the filter media. Effective filtration area is increased. When filter media as pleated and assembled in packs in other designs, grooved/projections on the filter media of two adjacent pleats overlap/come in contact with each other thereby reducing effective filtration area. However, in the filter of the invention, the grooves are not perpendicular to end pleats. Grooving in a zig - zag manner ensures that when two adjacent pleats overlap/come in contact during assembling then only central portion of grooving comes in contact. The center tube design also provides several advantages such as grooving helps in improving the strength of center tube, lesser thickness provides the same strength thereby resulting in saving of material, grooving helps in pleat distribution, in new design by providing fillet radius effective filtration area increased since less paper comes in contact with center tube. Element pack is joined with end caps through hot plate welding technique. In this technique end caps are heated against a hot surface, allowed to soften sufficiently to produce a good bond , then pressed together while bond sets. Paper and plastic caps become integral part by this joining technique. Viscosity of end caps decreases with time as it changes from a solid state to a liquid state under the action of heat. Once the melting point is attained after a certain time, if no temperature change occurs, the molten mass viscosity also remains constant for a certain time (10 to 20 min.), beyond which the thermal degradation of material may set in. As thermoplastic melt has the lowest viscosity (and consequently the highest fluidity), which is maintained for several minutes. This allows the paper to be injected into the melt. Special fixtures are employed to maintain parallelism, flatness of end caps and uniform embedment of the pleated filter paper. The apparatus for manufacture is given in Figure 1 in the form of a schematic. A special heating mechanism ensures the uniform melting of end cap at all the point in a lesser time with improved performance. In that machine ceramic workstation dies are there to locate end caps. Pre-molded end caps are used in this machine. Pre-molded end caps are placed in ceramic workstation die that is connected with slide mechanism. Complete machine is PLC controlled to ensure the exact cycle time execution of each operation at all the time. After putting the end cap slide moves from that position to cap heating zone. Heating mechanism heated the end cap upto a fixed programmed time depends upon type, design of filter and material of end cap used. In this process temperature of end cap and the distance between heating mechanism and end cap is very critical. All the critical process parameters dedicated to that pan number based upon the initial trials programmed in their logic control if anything goes wrong then machine will not working in that way it ensures the quality of product. Machine continuously monitored the temperature of end cap, which is our ultimate aim and it's a total closed loop system. When the heating of end cap takes place filter media pack is located in pack locator manually, which is connected to cylinder having pressure switch. Scope in present m/c is there to automate this operation. When the heating is completed then slide moves from that position to original position where filter media pack is embedded in that. After heating when work station die with end cap comes at the embedment station then instantly pack locating blocks comes forward to locate filter media pack for proper positioning of pack in end cap. Immediately cylinder moves downward embed the filter media pack in end cap. After pressing the pack in end cap pack locating blocks moves backward and pack locator moves upward. Natural air-cooling is sufficient to solidify the bond between pack and end cap. Same operation sequence repeated for second side of end cap. All the manual loading and unloading operations in this machine can be automated depending on the level of automation required. This machine includes a center tube insertor in case center tube is there in filter elements. Where center tube is not required special locating mandrel is there to locate and help to form the necessary shape and pleat distribution. The method for the manufacture of filters of the invention has several advantages hi that the joining technique is fast and can be easily used for mass commercial production. Also, the bonding between the thermoplastic end cap and the filter means cools at a speedier rate enabling the speeding up of the manufacturing process. The use of ultrasonic or heat welding also ensures that the operational costs and material costs are reduced. The overall variation hi height of the filters and the consistency of manufacture is also within an acceptable margin thereby reducing wastage. One method by which the metal free filters can be manufactured is hot melt welding. In this method, the end pleats of paper pack are joined with TPX 16 - 192 hot melt. IPX 16 -192 polyamide is a high melting thermoplastic resin. It exhibits good fuel / oil resistant and adhesion a variety of substrates. Softening point of hot melt is 167 ~ 177° C. The side sealing with hot melt eliminates the chance of leakage in the filter during use and enables easy disposing off by incineration of the final product after use. Another method of manufacture is to use ultrasonic joining. Sealing of end pleats is done by ultrasonic welding technique. This method of manufacture is speedy and economical. While earlier attempts to use ultrasonic joining were not successful due to the difficulty in obtaining uniform resin distribution, the method of the present invention enables uniform bonding strength at all the points. The use of ultrasonic joining is preferred since the machinery cost is low, waste or scrap is not generated, the final product can be easily disposed off by incineration after use while in use, the chances of leakage are eliminated. The filter felt (gasket) is itself cut using ultrasonic vibrations using special dies and punch designed for this specific purpose. The use of ultrasonic cutting enables good dimensional control while speeding up the rate of cutting of the gaskets. Another advantage of the use of ultrasonic cutting of sealed loose fibers is that during cutting, loose fibers across the outer and inner diameter is avoided thereby avoiding the migration of fibers to the engine side. The gasket is joined with end caps of filter with ultrasonic welding technique. Ultrasonic welding is an economical method for joining same or similar plastic based parts. They may not produce good bond if they contain specific fillers, particularly glass fiber if they are of a high concentration. This technique is rapid and can be fully automated. Welding occurs when high frequency (20 to 40 kHz) vibrational energy is directed to the interface between the two parts, creating localized molecular expansion causing the plastic to melt. Pressure is maintained between the two parts after vibration stops, and the melted polymer immediately solidifies. The entire welding process normally takes place in less than 2 seconds. It has a high strength, which sometimes approaches the strength of the base material. While polyamide absorbs moisture, which then has to be removed before the plastics can be converted into acceptable products, low concentrations, as specified by the plastic's supplier, are achieved through efficient drying systems and proper handling of the dried resin before and during molding. The simple tray dryers or mechanical convection hot -air - dryers that may be adequate for nonhygroscopic resins are simply not capable of removing water to the degree necessary for the proper processing of hygroscopic resins or their compounds, particularly during periods of high humidity. The effect of having excess moisture manifests itself in various ways, depending on the process being employed. The common result is a loss in both mechanical and physical properties, with splays, nozzle drool between shot-size control, sinks and other losses that may occur during processing. This is avoided by the method of the present invention. The melt processing temperature of nylon which is a preferred polyamide is in the range of 260 - 290°C. The use of nylon offers several distinct advantages such as high flow and toughness in thin sections, good weld strength and easy fill of complicated shapes, predictable mold and annealing shrinkage with reduced or no warpage, fast overall cycles with the resin being moldable in cold mold, good ejectability of the parts from the molds, good rework stability with reduced property losses on remolding of dry reworked resin blends. It is also another advantage that the processing conditions are unaffected by recycling high levels of blend. Also, multicavity tooling does not present any difficulties in achieving commercial tolerances. It is preferred that the pleating of the filter elements be zigzag. This enables the reduction of the housing height while retaining the same or greater filtration area. The saving in terms of height reduction of the element assembly and the housing are both in the range of 30 - 40%. The packaging cost is also reduced and the saving in the length of the center tube is up to 30 - 40%. Other associated manufacturing costs such as transportation costs from initial to final stage, painting cost, inventory costs, painting cycle times, bottom spring height are all reduced due to the use of zigzag pleating. Selection of material for end caps of metal free filters depends upon type of liquid (fuel/oil) used. Some test fuels shows stress cracking, embrittlement with certain types of thermoplastic when it comes in contact for certain period of time at test and operating temperatures. Some of the test fuels are hygroscopic in nature so it's necessary to check the behavior of test fuel while selection and finalization of materials for end caps. Automobile manufactures and material suppliers continuously searching and testing different grades of plastics which can be used with all types of fuels and they get very favorable results. Acetalcopolymer shows very good results with almost all the test fuels and oils. Thus, different polyanride grades and acetalcopolymer can be used for different end use application with the method of the invention. The filter media of the invention shows a burst strength of 5.2 kg/cm2 and a tensile strength of 10.2kg/cm with CD 5.4 kg/cm for cured paper. Given below in Table 1 are functional properties of the filter media of the invention. The experimental set up comprised passing test oil of MIL H 5606 grade with dust of size ISO 12103-A-3 medium at an inlet pressure of 1 bar and flow rate of 160 LPH through the filter media of the invention which comprised cured filter. The test temperature was ambient and the dust concentration was 0.5 gms/1. It was observed that the terminating pressure drop was 0.8 bar. The total oil passed was 46 litres. Table 1(Table Removed) The particulate efficiency as calculated according to ISO 12103-3 - A - 3 Medium at a dust addition rate of 0.5 gm/1 using test oil MIL -H-5606. The results are given in Table 2 below. Table 2 (Table Removed) Water separation efficiency was tested as per ISO standard ISO 4020/1/6.6. The test oil was HSD and the test temperature was ambient. The flow rate of the oil was 160 litres/hour and the water addition rate was 2% of the flow rate. The inlet pressure was 14.5 psi. the test was continued for 60 minutes and oil samples were taken out from outlet at 5 minute intervals. The sample bottles were cleaned and dried in a oven before collection of samples. The water was drained out every 5 minutes from the filter/housing by opening the drain valve. The oil samples were mixed, taken in a test tube and centrifuged for 30 minutes. The water separation efficiency was calculated according to the formula C = [(ax0.02)-b]/(ax0.02) Where a = sample volume and b = water level in test tube after centrifugation. The efficiency of water separation is given below in Table 3. Table 3 (Table Removed) WE CLAIM: 1. A novel filter media comprising hardwood and softwood fibers blended with about 10% of the total weight of the media of polyester fibers. 2. A fitter media as claimed in claim 1 wherein the filter media has base weight of about 220 GSM. 3. A filter media as claimed in claim 1 wherein the filter media is impregnated with a no cure resin comprising a mixture of methyl methacrylate and isobutyl methacrylate in an amount of up to 8% of the total weight of the filter media. 4. A filter media as claimed in claim 1 wherein conventional wet end additives, such as MF and starches, is incorporated in the filter media. 5. A filter media as claimed in claim 1 wherein silicone is added to the resin blend as a cross linking agent in an amount of up to 2% concentration by volume of the resin solution. 6. A filter comprising a filter element in a predetermined pattern and with two ends opposite each other, end caps being connected to said opposing ends of said filter element, said filter element comprising a filter media impregnated with a resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate in an amount of up to 8% of the total weight of the filter element. 7. A filter as claimed in claim 6 wherein silicone is added to the resin blend as a cross linking agent in an amount of up to 2% concentration by volume of the resin solution. 8. A filter as claimed in claim 6 wherein filter element comprises of filter paper pleated in the form of a zig-zag shape with dimples provided at even distances on the surface thereof so as to create interstitial spaces between succeeding pleats of the filter element. 9. A filter as claimed in claim 6 wherein the sealing is done by ultrasonic welding. 10. A filter as claimed in claim 6 wherein the sealing is done by heat welding. 11. A filter as claimed in claim 6 wherein the end caps comprise Poryamide grade end caps. 12. A filter as claimed in claim 6 wherein the end caps comprise metal end caps. 13. A filter as claimed in claim 6 wherein the sealing layer comprises conventional adhesive. 14. A filter as claimed in claim 6 wherein the paper filter element is joined to the polyamide end caps with hot plate joining technique. 15. A fitter as claimed in claim 6 wherein the cutting of the filter felt is carried out by ultrasonic cutting technique. 16. A method for the manufacture of a filter media for use in fuel filters said filter media comprising hardwood and softwood fibers blended with about 10% of the total weight of the media of polyester fibers, said method comprising blending a mixture of hardwood and softwood fibers and then blending up to 10 % by weight of the total media of polyester fibers, forming said blend into a roll, impregnating said filter media roll with a no cure resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate dissolved in water, drying said filter media and shaping said dried filter media roll as desired. 17. A method as claimed in claim 16 wherein silicone is added to the resin blend as a cross linking agent in an amount of up to 2% concentration by volume of the resin solution. 18. A novel resin composition comprising a mixture of methyl methacrylate and isobutyl methacrylate, the ratio of the two ingredients being in the range of 1 - 99: 99 -1 by weight. 19. Filter element substantially as described hereinbefore and with reference to the foregoing examples. 20. Filter substantially as described hereinbefore and with reference to the foregoing examples 21. Method for the manufacture of a filter element substantially as described hereinbefore and with reference to the foregoing examples 22. Resin composition substantially as described hereinbefore and with reference to the foregoing examples.

Documents:

1006-del-2002-abstract.pdf

1006-del-2002-claims.pdf

1006-DEL-2002-Correspondence-Others (11-02-2010).pdf

1006-del-2002-correspondence-others.pdf

1006-del-2002-correspondence-po.pdf

1006-del-2002-description (complete).pdf

1006-DEL-2002-Form-1-(11-02-2010).pdf

1006-del-2002-form-1.pdf

1006-del-2002-form-19.pdf

1006-DEL-2002-Form-2-(11-02-2010).pdf

1006-del-2002-form-2.pdf

1006-DEL-2002-Form-26-(11-02-2010).pdf

1006-del-2002-form-3.pdf

1006-del-2002-form-4.pdf

1006-del-2002-gpa.pdf