Wet lap composition and related processes

Abstract

A microfiber-containing wet lap composition is provided. The wet lap composition comprises a mixture of a sulfopolyester dispersion and a plurality of water nondispersible synthetic polymer microfibers. The microfibers have an equivalent diameter of less than 5 microns and a length of less than 25 millimeters. The sulfopolyester dispersion comprises at least one sulfopolyester and water.

1 . A microfiber-containing composition comprising:
 a mixture of a sulfopolyester dispersion and a plurality of water nondispersible synthetic polymer microfibers,   wherein said microfibers have an equivalent diameter of less than 5 microns and a length of less than 25 millimeters,   wherein said sulfopolyester dispersion comprises at least one sulfopolyester and water,   wherein said at least one sulfopolyester comprises:   (i) about 50 to about 96 percent, based on the total acid residues, of residues of one or more dicarboxylic acids, wherein said one or more dicarboxylic acids comprise terephthalic acid and isophthalic acid,   (ii) about 4 to about 40 mole percent, based on the total acid residues, of residues of at least one sulfomonomer having two 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, and   (iii) one or more diol residues,   wherein said sulfopolyester has a glass transition temperature of at least 40° C.,   wherein said sulfopolyester has an inherent viscosity of at least 0.2 dL/g measured in a 60/40 parts by weight solution of phenol/tetrachloroethane solvent at 40° C. and at a concentration of 0.5 grams of sulfopolyester in 100 mL of solvent,   wherein said sulfopolyester exhibits a melt viscosity of less than 10,000 poise measured at 240° C. at a strain rate of 1 rad/sec.   
     
     
         2 . The microfiber-containing composition of  claim 1  wherein said microfiber-containing composition consists essential of said sulfopolyester dispersion and said microfibers. 
     
     
         3 . The microfiber-containing composition of  claim 1  wherein said microfiber-containing composition consists of said sulfopolyester dispersion and said microfibers. 
     
     
         4 . The microfiber-containing composition of  claim 1  wherein excess water has been removed from said microfiber-containing composition. 
     
     
         5 . The microfiber-containing composition of  claim 4  wherein said excess water has been removed from said microfiber-containing composition by screening, filtering, and/or squeezing. 
     
     
         6 . The microfiber-containing composition of  claim 1  wherein said microfibers and said sulfopolyester are derived from multicomponents fibers having said microfibers as a water nondispersible component thereof and having said sulfopolyester as a water dispersible component thereof. 
     
     
         7 . The microfiber-containing composition of  claim 1  wherein said water of said sulfopolyester dispersion is distilled or deionized water. 
     
     
         8 . The microfiber-containing composition of  claim 1  wherein said water of said sulfopolyester dispersion is soft water. 
     
     
         9 . The microfiber-containing composition of  claim 1  wherein said sulfopolyester has a glass transition temperature of at least 50° C. and a melt viscosity of less than about 6,000 poise measured at 240° C. at a strain rate of 1 rad/sec. 
     
     
         10 . The microfiber-containing composition of  claim 1  wherein said sulfopolyester comprises about 80 to about 96 mole percent, based on the total acid residues, of residues of said one or more dicarboxylic acids. 
     
     
         11 . The microfiber-containing composition of  claim 1  wherein said sulfopolyester comprises about 4 to about 20 mole percent, based on the total acid residues, of residues of said at least one sulfomonomer. 
     
     
         12 . The microfiber-containing composition of  claim 1  wherein said at least one sulfomonomer is 5-sodiosulfoisophthalic acid. 
     
     
         13 . The microfiber-containing composition of  claim 1  wherein said microfibers have an equivalent diameter of less than 3 microns. 
     
     
         14 . The microfiber-containing composition of  claim 1  wherein said microfibers have a length of less than 3.5 millimeters. 
     
     
         15 . The microfiber-containing composition of  claim 1  wherein said microfibers are formed of a water non-dispersible material selected from the group consisting of polyolefins, polyesters, polyamides, polylactides, polycaprolactone, polycarbonate, polyurethane, cellulose ester, polyvinyl chloride, and mixtures thereof. 
     
     
         16 . The microfiber-containing composition of  claim 1  wherein said microfibers are formed of a polyester. 
     
     
         17 . A process for making a nonwoven article, said process comprising using said microfiber-containing composition of  claim 1  in a wet-laid nonwoven process. 
     
     
         18 . The process of  claim 17  wherein said using of said microfiber-containing composition in said wet-laid processes comprises mixing said microfiber-containing composition with water and transferring the resulting mixture to a wet-laid nonwoven zone. 
     
     
         19 . The process of  claim 17  wherein said using of said microfiber-containing composition in said wet-laid processes comprises mixing said microfiber-containing composition with water and additional fibers and transferring the resulting mixture to a wet-laid nonwoven zone 
     
     
         20 . A wet lap composition comprising water and a plurality of synthetic fibers, wherein said water makes up in the range of from 50 to 90 weight percent of said wet lap composition, wherein said synthetic fibers make up in the range of from 10 to 50 weight percent of said wet lap composition, wherein said water and said synthetic fibers in combination make up of at least 95 weight percent of said wet lap composition, wherein said synthetic fibers have a length of less than 25 millimeters and a minimum transverse dimension of less than 10 microns, wherein said synthetic fibers are formed of a water non-dispersible synthetic polymer. 
     
     
         21 . The wet lap composition of  claim 20  wherein said water makes up at least 55 weight percent and not more than 85 weight percent of said wet lap composition, wherein said synthetic fibers make up at least 15 weight percent and not more than 45 weight percent of said wet lap composition, wherein said water and said synthetic fibers in combination make up at least 98 weight percent of said wet lap composition. 
     
     
         22 . The wet lap composition of  claim 20  wherein said synthetic fibers have a length of not more than 10 millimeters. 
     
     
         23 . The wet lap composition of  claim 20  wherein said synthetic fibers have a minimum transverse dimension not more than 5 microns. 
     
     
         24 . The wet lap composition of  claim 20  further comprising a fiber finishing composition in an amount of at least 10 ppmw and not more than 1,000 ppmw. 
     
     
         25 . The wet lap composition of  claim 24  wherein said fiber finishing composition comprising an oil, a wax, and/or a fatty acid. 
     
     
         26 . The wet lap composition of  claim 24  wherein said fiber finishing composition comprises mineral oil, stearate esters, sorbitan esters, and/or neatsfoot oil. 
     
     
         27 . The wet lap composition of  claim 20  further comprising a water dispersible polymer in an amount of at least 0.001 and not more than 5 weight percent. 
     
     
         28 . The wet lap composition of  claim 27  wherein said water dispersible polymer comprises at least one a sulfopolyester. 
     
     
         29 . The wet lap composition of  claim 28  wherein at least one said sulfopolyester has a glass transition temperature of at least 40° C. and a melt viscosity of less than about 10,000 poise measured at 240° C. at a strain rate of 1 rad/sec, wherein said at least one sulfopolyester comprises:
 (i) about 50 to about 96 percent, based on the total acid residues, of residues of one or more dicarboxylic acids, wherein said one or more dicarboxylic acids comprise terephthalic acid and isophthalic acid, 
 (ii) about 4 to about 40 mole percent, based on the total acid residues, of residues of at least one sulfomonomer having two 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, and 
 (iii) one or more diol residues, 
 
     
     
         30 . The wet lap composition of  claim 20  wherein said water non-dispersible synthetic polymer is selected from the group consisting of polyolefins, polyesters, copolyesters, polyamides, polylactides, polycaprolactones, polycarbonates, polyurethanes, cellulose esters, acrylics, polyvinyl chlorides, and blends thereof. 
     
     
         31 . A wet-laid process to produce a nonwoven article, said wet-laid process comprising:
 (a) producing multicomponent fibers comprising at least one water dispersible sulfopolyester and one or more water non-dispersible synthetic polymers immiscible with said sulfopolyester, wherein said multicomponent fibers have an as-spun denier of less than 15 dpf;   (b) cutting said multicomponent fibers into cut multicomponent fibers having a length of less than 25 millimeters;   (c) contacting said cut multicomponent fibers with water to remove said sulfopolyester thereby forming a slurry of synthetic fibers in a sulfopolyester dispersion, wherein said sulfopolyester dispersion comprises water and at least a portion of said sulfopolyester; and   (d) removing at least a portion of said sulfopolyester dispersion from said slurry to thereby producing a wet lap composition, wherein said wet lap composition comprises water and a plurality of said synthetic fibers, wherein said water makes up in the range of from 50 to 90 weight percent of said wet lap composition, wherein said synthetic fibers make up in the range of from 10 to 50 weight percent of said wet lap composition, wherein said water and said synthetic fibers in combination make up of at least 95 weight percent of said wet lap composition, wherein said synthetic fibers have a length of less than 25 millimeters and an minimum transverse dimension of less than 5 microns.   
     
     
         32 . The wet-laid process of  claim 31 , further comprising transferring said wet lap composition to a wet-laid nonwoven zone to produce said nonwoven article. 
     
     
         33 . The wet-laid process of  claim 31  further comprising combining said wet lap composition with additional fibers in said wet-laid nonwoven zone and/or immediately upstream of said wet-laid nonwoven zone. 
     
     
         34 . The wet-laid process of  claim 33  wherein said addition fibers are selected from a group consisting of cellulosic fiber pulp, inorganic fibers, polyester fibers, nylon fibers, lyocell fibers, polyolefin fibers, rayon fibers, cellulose ester fibers, and combinations thereof. 
     
     
         35 . The wet-laid process of  claim 31  further comprising combining said wet lap composition with dilution water in said wet-laid nonwoven zone and/or immediately upstream of said wet-laid nonwoven zone, wherein said combining includes using at least 50 parts by weight of said dilution water per part of said wet lap composition. 
     
     
         36 . The wet-laid process of  claim 31  wherein said water makes up at least 55 weight percent and not more than 85 weight percent of said wet lap composition, wherein said synthetic fibers make up at least 15 weight percent and not more than 45 weight percent of said wet lap composition, wherein said water and said synthetic fibers in combination make up at least 98 weight percent of said wet lap composition. 
     
     
         37 . The wet-laid process of  claim 31  wherein said synthetic fibers have a length of at least 0.5 millimeter and not more than 10 millimeters, wherein said synthetic fibers have a minimum transverse dimension at least 0.5 microns and not more than 5 microns. 
     
     
         38 . The wet-laid process of  claim 31  wherein said wet lap composition further comprises said sulfopolyester in an amount of at least 0.001 weight percent and not more than 5 weight percent.