Fine particle liquid filtration media

Abstract

The present invention provides a filter media comprising (a) a nonwoven composite material comprising a stabilized mixture of thermoplastic microfibers and at least about 50%, by weight, of a secondary fibrous material such as pulp or polymeric staple fibers; (b) a first outer nonwoven web comprising a substantially uniform nonwoven web of autogenously bonded multicomponent fibers; and (c) a second outer nonwoven web wherein the nonwoven composite material is positioned between the first outer nonwoven web and second outer nonwoven web. The filter material is well suited to filtering liquid borne particulate matter ranging in size from 5μ to about 25μ.

What is claimed is:  
     
       1. Filtration media consisting essentially of: 
       a nonwoven composite material having a first and second side and comprising a stabilized matrix of thermoplastic microfibers having within said microfiber matrix at least about 50%, by weight, of a secondary material;  
       a first nonwoven web adjacent said first side of said nonwoven composite material wherein said first nonwoven web comprises a substantially uniform nowoven web having inter-fiber bonds throughout the web; and  
       a second nonwoven web adjacent said second side of said nonwoven composite material and wherein said first and second nonwoven webs and said nonwoven composite material comprise an integrated autogenously bonded multilayer laminate.  
     
     
       2. The filtration media of  claim 1  wherein said nonwoven composite material has a basis weight between about 30 g/m 2  and about 300 g/m 2 . 
     
     
       3. The filtration media of  claim 2  wherein said secondary material of the nonwoven composite material comprises a fibrous material selected from pulp, polymeric staple fibers, and feathers. 
     
     
       4. The filtration media of  claim 2  wherein said secondary material of the nonwoven composite material comprises a fibrous, non-polymeric material. 
     
     
       5. The filtration media of  claim 4  wherein said secondary material of the nonwoven composite material comprises pulp. 
     
     
       6. The filtration media of  claim 3  wherein said first nonwoven web comprises a nonwoven web of continuous fibers selected from the group consisting of multicomponent and multiconstituent fibers. 
     
     
       7. The filtration media of  claim 6  wherein said first nonwoven web comprises an autogenously bonded web of crimped multicomponent spunbond fibers having a density between about 0.01 g/cm 3  and about 0.2 g/cm 3 . 
     
     
       8. The filtration media of  claim 7  wherein said first nonwoven web of multicomponent spunbond fibers comprises a web of polyethylene/polypropylene bicomponent spunbond fibers. 
     
     
       9. The filtration media of  claim 8  wherein said second nonwoven web comprises a nonwoven web of continuous fibers selected from the group consisting of multicomponent and multiconstituent fibers. 
     
     
       10. The filtration media of  claim 8  wherein said composite material comprises meltblown fibers having an average fiber size less than about 15μ. 
     
     
       11. The filtration media of  claim 9  wherein said second nonwoven web comprises a substantially uniform, autogenously bonded nonwoven web of crimped multicomponent spunbond fibers and further wherein said fibers of said second nonwoven web comprise polyethylene and a second polymer. 
     
     
       12. The filtration media of  claim 11  wherein said first autogenously bonded nonwoven web has a basis weight between about 30 g/m 2  and 150 g/m 2 , and said second nonwoven web has a basis weight of between about 30 g/m 2  and 150 g/m 2 . 
     
     
       13. The filtration media of  claim 7  further comprising a third nonwoven web wherein said third nonwoven web comprises a substantially uniform and autogenously bonded nonwoven web of crimped multicomponent spunbond fibers and further wherein said third nonwoven web has a density greater than the density of said first nonwoven web. 
     
     
       14. The filtration media of  claim 13  wherein said nonwoven composite material has a basis weight between about 50 g/m 2  and 300 g/m 2 , said first and third nonwoven webs have a combined basis weight between about 50 g/m 2  and 150 g/m 2 , and said second nonwoven web a basis weight of between about 30 g/m 2  and 150 g/m 2 .