Dimensionally stable nonwoven fibrous webs and methods of making and using the same

Abstract

Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. When the thermoplastic polyester is selected to include aliphatic and aromatic polyesters, a spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. When the thermoplastic polyester is selected from aliphatic polyesters, a meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

1 - 41 . (canceled) 
     
     
         42 . A nonwoven web including a plurality of continuous fine fibers comprising:
 one or more thermoplastic aliphatic polyesters; and   polypropylene in an amount greater than 0% and no more than 10% by weight of the web;   wherein the fibers exhibit molecular orientation and extend substantially endlessly through the web, and have a median fiber diameter of no greater than 20 micrometers;   further wherein the web has at least one dimension which decreases by no greater than 10% when the web is heated to a temperature above a glass transition temperature of the fibers;   wherein the nonwoven web comprises at least one melt blown layer and at least one spunbond layer, at least one of which includes the fine fibers;   wherein the meltblown layer has further incorporated therein or thereon a repellent additive.   
     
     
         43 . The nonwoven web of  claim 42 , wherein the repellent additive comprises a surface treatment comprising paraffin waxes, fatty acids, bee's wax, silicones, fluorochemicals, and combinations thereof. 
     
     
         44 . The nonwoven web of  claim 42 , wherein the repellent additive is selected from a fluorochemical comprising a perfluoroalkyl group having at least 4 carbon atoms and a silicone fluid consisting of a linear polymer having a molecular weight of about 4000 to 25,000. 
     
     
         45 . The nonwoven web of  claim 42 , wherein the nonwoven web comprises a spunbond-meltblown-spunbond layered construction. 
     
     
         46 . The nonwoven web of  claim 42 , wherein the nonwoven web comprises a spunbond-meltblown-meltblown-spunbond layered construction. 
     
     
         47 . The nonwoven web of  claim 42 , wherein the molecular orientation of the fibers results in a bi-refringence value of at least 0.01. 
     
     
         48 . The nonwoven web of  claim 42 , wherein the thermoplastic aliphatic polyester is selected from the group consisting of one or more poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolic acid), polybutylene succinate, polyhydroxybutyrate, polyhydroxyvalerate, blends, and copolymers thereof. 
     
     
         49 . The nonwoven web of  claim 48 , wherein the aliphatic polyester is semicrystalline. 
     
     
         50 . The nonwoven web of  claim 42 , further comprising at least one of a plasticizer, a diluent, a surfactant, a viscosity modifier, an antimicrobial component, or combinations thereof. 
     
     
         51 . The nonwoven web of  claim 50 , wherein the plasticizer is selected from poly(ethylene glycol), oligomeric polyesters, fatty acid monoesters and di-esters, citrate esters, or combinations thereof. 
     
     
         52 . The nonwoven web of  claim 50 , wherein the diluent is selected from a fatty acid monoester (FAME), a poly(lactic acid) (PLA) oligomer, or combinations thereof. 
     
     
         53 . The nonwoven web of  claim 50 , wherein the surfactant is selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, or combinations thereof. 
     
     
         54 . The nonwoven web of  claim 50 , wherein the viscosity modifier has the following structure:
   (R—CO 2   − ) n M n+ 
   where R is alkyl or alkylene of C8-C30, which is branched or straight chain, or C12-C30 aralkyl and may be optionally substituted with 0-100 alkylene oxide groups, oligomeric lactic and/or glycolic acid, or a combination thereof;   n is the valency of M; and   M is H, an alkali metal or an alkaline earth metal salt, or amine salts.   
     
     
         55 . The nonwoven web of  claim 54 , wherein the viscosity modifier is selected from the group consisting of selected from the group consisting of alkyl carboxylates, alkenyl carboxylates, aralkyl carboxylates, alkylethoxylated carboxylates, aralkylethoxylated carboxylates, alkyl lactylates, alkenyl lactylates, stearoyl lactylates, stearates, and mixtures thereof. 
     
     
         56 . The nonwoven web of  claim 50 , wherein the antimicrobial component is selected from a fatty acid monoester, a fatty acid di-ester, an organic acid, a silver compound, a quaternary ammonium compound, a cationic (co)polymer, an iodine compound, or combinations thereof. 
     
     
         57 . The nonwoven web of  claim 42 , further comprising a thermoplastic (co)polymer distinct from the thermoplastic aliphatic polyester. 
     
     
         58 . The nonwoven web of  claim 42 , wherein the polypropylene is present in an amount from about 1% to about 6% by weight of the web. 
     
     
         59 . The nonwoven web of  claim 42 , wherein the fibers exhibit a median diameter of no greater than about 15 micrometers. 
     
     
         60 . The nonwoven web of  claim 42 , wherein the web is autogeneously bonded. 
     
     
         61 . A nonwoven web including a plurality of fine fibers comprising:
 one or more thermoplastic polyesters selected from aliphatic polyesters; and   polypropylene in an amount greater than 0% and no more than 10% by weight of the web;   wherein the fibers do not exhibit molecular orientation, and have a median fiber diameter of no greater than 20 micrometers;   further wherein the web has at least one dimension which decreases by no greater than 10% when the web is heated to a temperature above a glass transition temperature of the fibers;   wherein the nonwoven web comprises at least one melt blown layer and at least one spunbond layer, at least one of which includes the fine fibers;   wherein the meltblown layer has further incorporated therein or thereon a repellent additive.   
     
     
         62 . The nonwoven web of  claim 61 , wherein the repellent additive comprises a surface treatment comprising paraffin waxes, fatty acids, bee's wax, silicones, fluorochemicals, and combinations thereof. 
     
     
         63 . The nonwoven web of  claim 61 , wherein the repellent additive is selected from a fluorochemical comprising a perfluoroalkyl group having at least 4 carbon atoms and a silicone fluid consisting of a linear polymer having a molecular weight of about 4000 to 25,000. 
     
     
         64 . The nonwoven web of  claim 61 , wherein the nonwoven web comprises a spunbond-meltblown-spunbond layered construction. 
     
     
         65 . The nonwoven web of  claim 61 , wherein the nonwoven web comprises a spunbond-meltblown-meltblown-spunbond layered construction. 
     
     
         66 . The nonwoven web of  claim 61 , wherein the thermoplastic aliphatic polyester is selected from the group consisting of one or more poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolic acid), polybutylene succinate, polyhydroxybutyrate, polyhydroxyvalerate, blends, and copolymers thereof. 
     
     
         67 . The nonwoven web of  claim 66 , wherein the aliphatic polyester is semicrystalline. 
     
     
         68 . The nonwoven web of  claim 61 , further comprising at least one of a plasticizer, a diluent, a surfactant, a viscosity modifier, an antimicrobial component, or combinations thereof. 
     
     
         69 . The nonwoven web of  claim 68 , wherein the plasticizer is selected from poly(ethylene glycol), oligomeric polyesters, fatty acid monoesters and di-esters, citrate esters, or combinations thereof. 
     
     
         70 . The nonwoven web of  claim 68 , wherein the diluent is selected from a fatty acid monoester (FAME), a poly(lactic acid) (PLA) oligomer, or combinations thereof. 
     
     
         71 . The nonwoven web of  claim 68 , wherein the surfactant is selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, or combinations thereof. 
     
     
         72 . The nonwoven web of  claim 68 , wherein the viscosity modifier has the following structure:
   (R—CO 2   − ) n M n+ 
   where R is alkyl or alkylene of C8-C30, which is branched or straight chain, or C12-C30 aralkyl and may be optionally substituted with 0-100 alkylene oxide groups, oligomeric lactic and/or glycolic acid, or a combination thereof;   n is the valency of M; and   M is H, an alkali metal or an alkaline earth metal salt, or amine salts.   
     
     
         73 . The nonwoven web of  claim 72 , wherein the viscosity modifier is selected from the group consisting of selected from the group consisting of alkyl carboxylates, alkenyl carboxylates, aralkyl carboxylates, alkylethoxylated carboxylates, aralkylethoxylated carboxylates, alkyl lactylates, alkenyl lactylates, stearoyl lactylates, stearates, and mixtures thereof. 
     
     
         74 . The nonwoven web of  claim 68 , wherein the antimicrobial component is selected from a fatty acid monoester, a fatty acid di-ester, an organic acid, a silver compound, a quaternary ammonium compound, a cationic (co)polymer, an iodine compound, or combinations thereof. 
     
     
         75 . The nonwoven web of  claim 61 , further comprising a thermoplastic (co)polymer distinct from the thermoplastic aliphatic polyester. 
     
     
         76 . The nonwoven web of  claim 61 , wherein the polypropylene is present in an amount from about 1% to about 6% by weight of the web. 
     
     
         77 . The nonwoven web of  claim 61 , wherein the fibers exhibit a median diameter of no greater than about 15 micrometers. 
     
     
         78 . The nonwoven web of  claim 61 , wherein the web is autogeneously bonded. 
     
     
         79 . An article comprising the nonwoven web of  claim 42 , wherein the article is a gas filtration article, a liquid filtration article, a sound absorption article, a thermal insulation article, a surface cleaning article, a cellular growth support article, a drug delivery article, or a personal hygiene article. 
     
     
         80 . An article comprising the nonwoven web of  claim 42 , wherein the article is a surgical drape, a surgical gown, a sterilization wrap, or a wound contact material. 
     
     
         81 . An article comprising the nonwoven web of  claim 42  and a support layer, wherein the nonwoven web and the support layer are bonded using thermal bonding, adhesive bonding, powdered binder bonding, hydroentangling, needlepunching, calendaring, or a combination thereof. 
     
     
         82 . An article comprising the nonwoven web of  claim 61 , wherein the article is a gas filtration article, a liquid filtration article, a sound absorption article, a thermal insulation article, a surface cleaning article, a cellular growth support article, a drug delivery article, or a personal hygiene article. 
     
     
         83 . An article comprising the nonwoven web of  claim 61 , wherein the article is a surgical drape, a surgical gown, a sterilization wrap, or a wound contact material. 
     
     
         84 . An article comprising the nonwoven web of  claim 61  and a support layer, wherein the nonwoven web and the support layer are bonded using thermal bonding, adhesive bonding, powdered binder bonding, hydroentangling, needlepunching, calendaring, or a combination thereof. 
     
     
         85 . A method of making a nonwoven web according to  claim 42  comprising:
 forming a mixture of one or more thermoplastic aliphatic polyesters with polypropylene in an amount greater than 0% and no more than 10% by weight of the mixture; 
 forming a plurality of fibers from the mixture; and 
 collecting at least a portion of the fibers to form a web, wherein the fibers exhibit molecular orientation and extend substantially endlessly through the web, and further wherein the web has at least one dimension which decreases by no greater than 10% when the web is heated to a temperature above a glass transition temperature of the fibers. 
 
     
     
         86 . A method of making a nonwoven web according to  claim 61  comprising:
 forming a mixture of one or more thermoplastic aliphatic polyesters with polypropylene in an amount greater than 0% and no more than 10% by weight of the mixture; 
 forming a plurality of fibers from the mixture; and 
 collecting at least a portion of the fibers to form a web, wherein the fibers do not exhibit molecular orientation, and further wherein the web has at least one dimension which decreases by no greater than 10% when the web is heated to a temperature above a glass transition temperature of the fibers.