Process for making nonwoven webs

Abstract

A nonwoven web comprising bicomponent fibers. The fibers have continuous phases each of a first polyarylene sulfide (PAS) component and a polymer component. The polymer component may also be a second polyarylene sulfide. The first polyarylene sulfide component contains a tin or a zinc additive or both, and the first polyarylene sulfide component of any given fiber is at least partially exposed to the external surface of that fiber.

1 . A process for manufacturing a nonwoven web comprising the steps of (i) spinning bicomponent fibers into a nonwoven web, said fibers comprising continuous phases each of a first polyarylene sulfide (PAS) component and a polymer component, in which the first polyarylene sulfide component contains a tin or a zinc additive or both, and the first polyarylene sulfide component of any given fiber is at least partially exposed to the external surface of that fiber, and (ii) calendaring the nonwoven web. 
     
     
         2 . The process of  claim 1  in which the step of spinning is a spunbond process. 
     
     
         3 . The process of  claim 1  in which the polymer component comprises a polymer selected from the group consisting or polyether ether ketone (PEEK), polyether ketone (PEK), polyester, polypropylene, polyamide, and mixtures thereof. 
     
     
         4 . The process of  claim 3  in which the polyester comprises polyethylene terephthalate (PET), polytrimethylene terephthalate, or polybutylene terephthalate (PBT). 
     
     
         5 . The process of  claim 1  in which the second polymer component comprises a second polyarylene sulfide. 
     
     
         6 . The process of  claim 5  in which the second polyarylene sulfide is blended with a calcium salt. 
     
     
         7 . The process of  claim 6  in which the calcium salt is calcium stearate. 
     
     
         8 . The process of  claim 1  in which the tin additive is a branched carboxylate selected from the group consisting of Sn(O 2 CR) 2 , Sn(O 2 CR)(O 2 CR′), Sn(O 2 CR)(O 2 CR″), and mixtures thereof, where the carboxylate moieties O 2 CR and O 2 CR′ independently represent branched carboxylate anions and the carboxylate moiety O 2 CR″ represents a linear carboxylate anion 
     
     
         9 . The process of  claim 8  in which tin additive further comprises a linear tin(II) carboxylate Sn(O 2 CR″) 2    
     
     
         10 . The process of  claim 8  in which the sum of the branched carboxylate moieties O 2 CR and O 2 CR′ is at least about 25% on a molar basis of the total carboxylate moieties O 2 CR, O 2 CR′ and O 2 CR″ contained in the tin additive. 
     
     
         11 . The process of  claim 8  in which the radical R″ is a primary alkyl group comprising from 6 to 30 carbon atoms. 
     
     
         12 . The process of  claim 11  in which the radical R″ is substituted with a group selected form the group consisting of fluoride, chloride, bromide, iodide, nitro, hydroxyl, carboxylate, and any combination thereof. 
     
     
         13 . The process of  claim 8  in which the radicals R and R′ independently or both have a structure represented by Formula (I), 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , and R 3  are selected from the group consisting of:
 H; 
 a primary, secondary, or tertiary alkyl group having from 6 to 18 carbon atoms, optionally substituted with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups; 
 an aromatic group having from 6 to 18 carbon atoms, optionally substituted with alkyl, fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups; and 
 a cycloaliphatic group having from 6 to 18 carbon atoms, optionally substituted with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups; 
 with the proviso that when R 2  and R 3  are H, R 1  is: 
 a secondary or tertiary alkyl group having from 6 to 18 carbon atoms, optionally substituted with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups; 
 an aromatic group having from 6 to 18 carbons atoms and substituted with a secondary or tertiary alkyl group having from 6 to 18 carbon atoms, the aromatic group and/or the secondary or tertiary alkyl group being optionally substituted with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups; and 
 a cycloaliphatic group having from 6 to 18 carbon atoms, optionally substituted with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups. 
 
     
     
         14 . The process of  claim 8  in which the radicals R and R′ independently or both have a structure represented by Formula (I), and R 3  is H. 
     
     
         15 . The process of  claim 8  in which the radicals R and R′ independently or both have a structure represented by Formula (II), 
       
         
           
           
               
               
           
         
       
       wherein
 R 4  is a primary, secondary, or tertiary alkyl group having from 4 to 6 carbon atoms, optionally substituted with fluoride, chloride, bromide, iodide, nitro, and hydroxyl groups; and 
 R 5  is a methyl, ethyl, n-propyl, sec-propyl, n-butyl, sec-butyl, or tert-butyl group, optionally substituted with fluoride, chloride, bromide, iodide, nitro, and hydroxyl groups. 
 
     
     
         16 . The process of  claim 8  in which the radicals R and R′ are the same and both have a structure represented by Formula (II), R 4  is n-butyl, and R 5  is ethyl. 
     
     
         17 . The process of  claim 1  in which the tin additive is present at a concentration of about 10 weight percent or less of the weight of the first polyarylene sulfide component. 
     
     
         18 . The process of  claim 1  in which the zinc additive comprises a zinc(II) additive or zinc metal [Zn(O)] or a mixture of both. 
     
     
         19 . The process of  claim 18  in which the zinc(II) additive is an organic additive or an inorganic additive or a mixture of both. 
     
     
         20 . The process of  claim 19 , wherein the Zn(II) additive is selected from the group consisting of zinc oxide, zinc stearate, zinc sulfate and mixtures thereof. 
     
     
         21 . The process of  claim 1 , wherein the zinc and tin additives are present at a total concentration of equal to or less than about 25 weight percent, based on the weight of the polyarylene sulfide. 
     
     
         22 . The process of  claim 21 , wherein the Zn(II) additive and zinc metal are present at a total concentration of zero to about about 10 weight percent or less, based on the weight of the polyarylene sulfide. 
     
     
         23 . The process of  claim 5 , wherein the first polyarylene sulfide, or the second polyarylene sulfide, or both are polyphenylene sulfide. 
     
     
         24 . The process of  claim 1  comprising calendaring the nonwoven web for a time and temperature sufficient to bond at least a subset of the individual fibers.