Nonwoven web with improved adhesion and reduced dust formation

Abstract

Making suitable nonwoven webs requires good adhesion between the binder and the absorbent material. The present invention relates to a nonwoven web having improved adhesion based on tackifiers present in the binder. Optionally, the binder with tackifier may also contain an adhesion promoter, usually grafted polyolefins, and an enhancement agent, usually inactive inorganic compounds in powder form. The web comprises from about 5 to about 25% by weight binder fiber and from about 75 to 95% by weight absorbent. The absorbent may be a natural absorbent or a super absorbent polymer or a combination of these. The binder fiber contains less than about 40% by weight tackifier. Tackifier is selected from the class of rosin, rosin esters, terpene based, piperylene based, and hydrocarbon based compounds.

1 . An improved binder fiber comprising a low melt polyolefin base with tackifier, wherein said low melt polyolefin base is low melt fiber, the low melting portion of bicomponent fiber, or both, and is selected from a group consisting of polyethylene, polypropylene, polybutylene, or a mixture thereof.  
     
     
         2 . The improved binder fiber of  claim 1 , wherein said tackifier is selected from the class of rosin, rosin esters, terpene based, piperylene based, and hydrocarbon based compounds.  
     
     
         3 . The improved binder fiber of  claim 1 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         4 . The improved binder fiber of  claim 3 , wherein said high melting portion is polyester.  
     
     
         5 . The improved binder fiber of  claim 3 , wherein said high melting portion is polyolefin.  
     
     
         6 . The improved binder fiber of  claim 1 , wherein said tackifier comprises from about 0.1 to about 40% by weight of said low melt base.  
     
     
         7 . The improved binder fiber of  claim 6 , wherein said tackifier comprises at least 2.5% by weight of said low melt base.  
     
     
         8 . The binder fiber of  claim 3 , wherein said low melt base comprises from about 5% to about 75% by weight of said bicomponent fiber.  
     
     
         9 . The improved binder fiber of  claim 1 , wherein said polyolefin base is polyethylene and is selected from the class of HDPE, MDPE, LDPE, LLDPE, ULDPE, or mixtures of these.  
     
     
         10 . The improved binder fiber of  claim 1 , wherein said low melt polymer fiber consists essentially of said low melt base and said tackifier.  
     
     
         11 . The improved binder fiber of  claim 1 , wherein said low melt base additionally comprises an adhesion promoter.  
     
     
         12 . The improved binder fiber of  claim 11 , wherein said adhesion promoter is selected from the class of maleic acid or maleic anhydride grafted polyolefin, ethylene-acrylic copolymers, or a combination of these.  
     
     
         13 . The improved binder fiber of  claim 12 , wherein said grafted polyolefin contains incorporated maleic acid or maleic anhydride in the range from about 0.05 to about 2.0 weight % of said low melt base.  
     
     
         14 . The improved binder fiber of  claim 12 , wherein said ethylene-acrylic copolymers are present in a range of about 1 to about 20 weight % of said low melt base.  
     
     
         15 . The improved binder fiber of  claim 11 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         16 . The improved binder fiber of  claim 15 , wherein said high melting portion is polyester.  
     
     
         17 . The improved binder fiber of  claim 15 , wherein said high melting portion is polyolefin.  
     
     
         18 . The improved binder fiber of  claim 1 , additionally comprising an enhancement agent in said low melt base.  
     
     
         19 . The improved binder fiber of  claim 18 , wherein said enhancement agent is selected from the class of titanium dioxide, talc, silica, alum, calcium carbonate, calcium oxide, and magnesium oxide.  
     
     
         20 . The improved binder fiber of  claim 18 , wherein said enhancement agent is present in a range of about 0.1 to 1.0 weight % of said low melt base.  
     
     
         21 . The improved binder fiber of  claim 18 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         22 . The improved binder fiber of  claim 21 , wherein said high melting portion is polyester.  
     
     
         23 . The improved binder fiber of  claim 21 , wherein said high melting portion is polyolefin.  
     
     
         24 . A nonwoven web comprising binder fiber and absorbent, said binder fiber comprising a low melt polyolefin base with tackifier, wherein said low melt polyolefin base is low melt fiber, the low melting portion of bicomponent fiber, or both, and is selected from a group consisting of polyethylene, polypropylene, polybutylene, or a mixture thereof.  
     
     
         25 . The web of  claim 24 , wherein said binder fiber is from about 5 to about 25 weight % of said web.  
     
     
         26 . The web of  claim 24 , wherein said absorbent comprises natural absorbents, super absorbent polymer, or both.  
     
     
         27 . The web of  claim 24 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         28 . The web of  claim 27 , wherein said high melting portion is polyester.  
     
     
         29 . The web of  claim 27 , wherein said high melting portion is polyolefin.  
     
     
         30 . The web of  claim 24 , wherein said tackifier comprises from about 0.1 to about 40 % by weight of said low melt base.  
     
     
         31 . The web of  claim 24 , wherein said tackifier is selected form the class of rosin, rosin esters, terpene based, piperylene based, and hydrocarbon based compounds.  
     
     
         32 . The web of  claim 24 , wherein said low melt polymer fiber is substantially low melt base and said tackifier.  
     
     
         33 . The web of  claim 24 , wherein said polyethylene is selected from the class of HDPE, MDPE, LDPE, LLDPE, ULDPE, or mixtures of these.  
     
     
         34 . The web of  claim 24 , additionally comprising an adhesion promoter in said low melt base.  
     
     
         35 . The web of  claim 34 , wherein said adhesion promoter is selected from the class of maleic acid or maleic anhydride grafted polyolefin, ethylene-acrylic copolymers, or a combination of these.  
     
     
         36 . The web of  claim 35 , wherein said grafted polyolefin contains incorporated maleic acid or maleic anhydride in the range from about 0.05 to about 2.0 weight % of said low melt base.  
     
     
         37 . The web of  claim 35 , wherein said ethylene-acrylic copolymers are present in a range of about 1 to about 20 weight % of said low melt base.  
     
     
         38 . The web of  claim 34 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         39 . The web of  claim 38 , wherein said high melting portion is polyester.  
     
     
         40 . The web of  claim 38 , wherein said high melting portion is polyolefin.  
     
     
         41 . The web of  claim 24 , wherein said low melt base also contains enhancement agent.  
     
     
         42 . The web of  claim 41 , wherein said enhancement agent is selected from the class of titanium dioxide, talc, silica, alum, calcium carbonate, calcium oxide, and magnesium oxide.  
     
     
         43 . The web of  claim 41 , wherein said enhancement agent is present in a range from about 0.1 to 1.0 weight % of said low melt base.  
     
     
         44 . The web of  claim 41 , wherein said bicomponent fiber has a high melting portion selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         45 . The web of  claim 44 , wherein said high melting portion is polyester.  
     
     
         46 . The web of  claim 44 , wherein said high melting portion is polyolefin.