Short cut microfibers

Abstract

A short-cut, water non-dispersible polymer microfiber is provided comprising at least one water non-dispersible polymer wherein the water non-dispersible polymer microfiber has an average fineness of less than 1 denier per filament; and wherein said water non-dispersible short-cut polymer microfiber has an aspect ratio of about 300 to about 1000. A process for producing water non-dispersible polymer microfibers and a process for producing nonwoven articles are also provided.

1 . A water non-dispersible short-cut polymer microfiber comprising at least one water non-dispersible polymer; wherein said water non-dispersible short-cut polymer microfiber has an average fineness of less than 1 denier per filament; and wherein said water non-dispersible short-cut polymer microfiber has an aspect ratio of about 300 to about 1000. 
     
     
         2 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said water non-dispersible short-cut polymer microfiber has an aspect ratio of about 300 to about 750. 
     
     
         3 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said water non-dispersible short-cut polymer microfiber has an aspect ratio of about 300 to about 650. 
     
     
         4 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said water non-dispersible short-cut polymer microfiber has an aspect ratio of about 300 to about 550. 
     
     
         5 . A short-cut microfiber-containing mixture according to  claim 1  wherein said water non-dispersible short-cut polymer microfibers have a fineness of 0.5 d/f or less. 
     
     
         6 . A short-cut microfiber-containing mixture according to  claim 1  wherein said water non-dispersible short-cut polymer microfibers have a fineness of 0.1 d/f or less. 
     
     
         7 . A water non-dispersible short-cut polymer microfiber according to  claim 1  produced by the process comprising:
 a) providing a short-cut multicomponent fiber having a shaped cross section, said multicomponent fiber comprising:
 at least one water dispersible sulfopolyester; and 
 a plurality of microfiber domains comprising one or more water non-dispersible polymers immiscible with said sulfopolyester, wherein said microfiber domains are substantially isolated from each other by said sulfopolyester intervening between said microfiber domains; and 
 
 b) separating said water non-dispersible short-cut polymer microfiber from said water dispersible sulfopolyester. 
 
     
     
         8 . A water non-dispersible short-cut polymer microfiber according to  claim 7  wherein said short-cut multicomponent fiber has a shaped cross section, comprising:
 (A) at least one water dispersible sulfopolyester; and 
 (B) a plurality of microfiber domains comprising one or more water non-dispersible polymers immiscible with the sulfopolyester, wherein the microfiber domains are substantially isolated from each other by the sulfopolyester intervening between the microfiber domains, 
 
       wherein the water dispersible sulfopolyesters exhibits a melt viscosity of less than about 12,000 poise measured at 240° C. at a strain rate of 1 rad/sec, and wherein the sulfopolyester comprises less than about 25 mole % of residues of at least one sulfomonomer, based on the total moles of diacid or diol residues. 
     
     
         9 . A water non-dispersible short-cut polymer microfiber according to  claim 7  wherein said short-cut multicomponent fiber has a shaped cross section, comprising:
 (A) a water dispersible sulfopolyester having a glass transition temperature (Tg) of at least 57° C., the sulfopolyester comprising:
 (i) residues of one or more dicarboxylic acids; 
 (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; 
 (iii) one or more diol residues wherein at least 25 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure
   H—(OCH 2 —CH 2 ) n —OH
 
 
 
 wherein n is an integer in the range of 2 to about 500; and
 (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; and 
 
 (B) a plurality of microfiber domains comprising one or more water non-dispersible polymers immiscible with the sulfopolyester, wherein the microfiber domains are substantially isolated from each other by the sulfopolyester intervening between the microfiber domains. 
 
     
     
         10 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said short-cut polymer microfiber is a monocomponent microfiber. 
     
     
         11 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said water non-dispersible polymer microfiber comprises at least one polymer selected from the group consisting of polyolefins, polyesters, polyamides, polylactides, polycaprolactone, polycarbonate, polyurethane, cellulose esters, and polyvinyl chloride. 
     
     
         12 . A water non-dispersible short-cut polymer microfiber according to  claim 1  wherein said water non-dispersible polymer microfiber comprises at least one polymer selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), homo- and copolymers of polyethylene, homo- and copolymers of polypropylene, and nylon-6. 
     
     
         13 . A water non-dispersible short-cut polymer microfiber according to  claim 7  wherein said multicomponent fiber has an islands-in-the-sea, sheath core, side-by-side, or segmented pie configuration. 
     
     
         14 . A water non-dispersible short-cut polymer microfiber according to  claim 7  wherein said water dispersible component comprises a sulfopolyester. 
     
     
         15 . A water non-dispersible short-cut polymer microfiber according to  claim 14  wherein said sulfopolyester exhibits a glass transition temperature of at least 40° C. 
     
     
         16 . A water non-dispersible short-cut polymer microfiber according to  claim 15  wherein said sulfopolyester exhibits a melt viscosity of less than about 12,000 poise measured at 240° C. at a strain rate of 1 rad/sec. 
     
     
         17 . A nonwoven article comprising said water non-dispersible short-cut polymer microfiber of  claim 1 . 
     
     
         18 . A nonwoven article of  claim 17  wherein said nonwoven article is produced by a dry-laid process or wet-laid process. 
     
     
         19 . A nonwoven article according to  claim 17  wherein said water non-dispersible short-cut polymer microfiber comprises at least one polymer selected from the group consisting of polyolefins, polyesters, polyamides, polylactides, polycaprolactone, cellulose esters, polycarbonate, polyurethane, and polyvinyl chloride. 
     
     
         20 . A nonwoven article according to  claim 17  wherein said nonwoven article is an article selected from the group consisting of filter media for air filtration, filter media for water filtration, filter media for bodily fluid filtration, filter media for solvent filtration, filter media for hydrocarbon filtration, filter media for paper making processes, nonwoven fabrics, nonwoven webs, wet-laid webs, dry-laid webs, melt blown webs, spunbonded webs, thermobonded webs, hydroentangled webs, artificial leathers, suedes, cleaning wipes, multilayer nonwovens, laminates, composites, gauzes, bandages, diapers, training pants, tampons, surgical gowns, surgical masks, feminine napkins, replacement inserts for personal hygiene products, replacement inserts for cleaning products, filter media for food preparation, filter media for medical applications, and paper products.