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 form the class of rosin, rosin esters, terpene based, piperylene based, and hydrocarbon based compounds.

What is claimed is:  
     
         1 ) An improved adhesion binder comprising the combination of a binder fiber containing low melt base and tackifier, said low melt base is low melt polymer fiber, the low melting portion of bicomponent fiber, or both.  
     
     
         2 ) The improved binder 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 of  claim 1 , wherein said bicomponent fiber has a high melting portion.  
     
     
         4 ) The improved binder of  claim 3 , wherein said high melting portion is selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         5 ) The improved binder of  claim 4 , wherein said high melting portion is polyester.  
     
     
         6 ) The improved binder of  claim 4 , wherein said high melting portion is polyolefin.  
     
     
         7 ) The improved binder of  claim 1 , wherein said tackifier comprises from about 0.1 to about 40% by weight of said low melt base.  
     
     
         8 ) The binder of  claim 3 , wherein said low melting portion comprises from about 5% to about 75% by weight of said bicomponent fiber.  
     
     
         9 ) The improved binder of  claim 1 , wherein said low melt base is selected from the class of polyethylene, polypropylene, polybutylene, polyesters, copolyesters, or a mixture thereof.  
     
     
         10 ) The improved binder of  claim 9 , wherein said polyethylene is selected from the class of HDPE, MDPE, LDPE, LLDPE, ULDPE, or mixtures of these.  
     
     
         11 ) The improved binder of  claim 9 , wherein said polyesters and said copolyesters are selected from the class of as polybutylene terephthalate (PBT), or polytrimethylene terephthalate (PTT), a low melting copolyester such as copolymers of PET with comonomers such as suitable diol components selected from 1,4-cyclohexanedimenthanol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,2-dimenthyl-1,3-propanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and diols containing one or more oxygen atoms in the chain, such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, or mixtures of these; or one or more diacid components other than terephthalic acid, (aliphatic, alicyclic, or aromatic dicarboxylic acids) such as isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, bibenzoic acid, or mixtures of these.  
     
     
         12 ) The improved binder of  claim 1 , wherein said low melt polymer fiber is substantially said low melt base and said tackifier.  
     
     
         13 ) The improved binder of  claim 1 , additionally comprising an adhesion promoter in said low melt base.  
     
     
         14 ) The improved binder of  claim 13 , 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.  
     
     
         15 ) The improved binder of  claim 14 , 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.  
     
     
         16 ) The improved binder of  claim 14 , wherein said ethylene-acrylic copolymers are present in a range of about 1 to about 20 weight % of said low melt base.  
     
     
         17 ) The improved binder of  claim 13 , wherein said bicomponent fiber has a high melting portion.  
     
     
         18 ) The improved binder of  claim 17 , wherein said high melting portion is selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         19 ) The improved binder of  claim 18 , wherein said high melting portion is polyester.  
     
     
         20 ) The improved binder of  claim 18 , wherein said high melting portion is polyolefin.  
     
     
         21 ) The improved binder of  claim 1 , additionally comprising an enhancement agent in said low melt base.  
     
     
         22 ) The improved binder of  claim 21 , wherein said enhancement agent is selected from the class of titanium dioxide, talc, silica, alum, calcium carbonate, calcium oxide, and magnesium oxide.  
     
     
         23 ) The improved binder of  claim 21 , wherein said enhancement agent is present in a range of about 0.1 to 1.0 weight % of said low melt base.  
     
     
         24 ) The improved binder of  claim 21 , wherein said bicomponent fiber has a high melting portion.  
     
     
         25 ) The improved binder of  claim 24 , wherein said high melting portion is selected from the class of polyamide, polyester, polyolefin, polyacrylate, and mixtures thereof.  
     
     
         26 ) The improved binder of  claim 25 , wherein said high melting portion is polyester.  
     
     
         27 ) The improved binder of  claim 25 , wherein said high melting portion is polyolefin.  
     
     
         28 ) A nonwoven web comprising binder fiber and absorbent, said binder fiber containing tackifier and low melt base, said low melt base is low melt polymer fiber, the low melting component of bicomponent fiber, or both.  
     
     
         29 ) The web of  claim 28 , wherein said binder fiber is from about 5 to about 25 weight % of said web.  
     
     
         30 ) The web of  claim 28 , wherein said absorbent comprises natural absorbents, super absorbent polymer, or both.  
     
     
         31 ) The web of  claim 28 , wherein said bicomponent fiber has a high melting portion.  
     
     
         32 ) The web of  claim 31 , wherein said high melting portion is selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         33 ) The web of  claim 32 , wherein said high melting portion is polyester.  
     
     
         34 ) The web of  claim 32 , wherein said high melting portion is polyolefin.  
     
     
         35 ) The web of  claim 28 , wherein said tackifier comprises from about 0.1 to about 40% by weight of said low melt base.  
     
     
         36 ) The web of  claim 28 , wherein said tackifier is selected form the class of rosin, rosin esters, terpene based, piperylene based, and hydrocarbon based compounds.  
     
     
         37 ) The web of  claim 28 , wherein said low melt polymer fiber is substantially low melt base and said tackifier.  
     
     
         38 ) The web of  claim 28 , wherein said low melt base is selected from the class of polyethylene, polypropylene, polyesters, or copolyesters, or a mixture thereof.  
     
     
         39 ) The web of  claim 38 , wherein said polyethylene is selected from the class of HDPE, MDPE, LDPE, LLDPE, ULDPE, or mixtures of these.  
     
     
         40 ) The web of  claim 38 , wherein said polyesters and said copolyesters are selected from the class of as polybutylene terephthalate (PBT), or polytrimethylene terephthalate (PTT), a low melting copolyester such as copolymers of PET with comonomers such as suitable diol components selected from 1,4-cyclohexanedimenthanol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,2-dimenthyl-1, 3-propanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and diols containing one or more oxygen atoms in the chain, such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, or mixtures of these; or one or more diacid components other than terephthalic acid, (aliphatic, alicyclic, or aromatic dicarboxylic acids) such as isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, bibenzoic acid, or mixtures of these.  
     
     
         41 ) The web of  claim 28 , additionally comprising an adhesion promoter in said low melt base.  
     
     
         42 ) The web of  claim 41 , 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.  
     
     
         43 ) The web of  claim 42 , 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.  
     
     
         44 ) The web of  claim 42 , wherein said ethylene-acrylic copolymers are present in a range of about 1 to about 20 weight % of said low melt base.  
     
     
         45 ) The web of  claim 41 , wherein said bicomponent fiber has a high melting portion.  
     
     
         46 ) The web of  claim 45 , wherein said high melting portion is selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         47 ) The web of  claim 46 , wherein said high melting portion is polyester.  
     
     
         48 ) The web of  claim 46 , wherein said high melting portion is polyolefin.  
     
     
         49 ) The web of  claim 28 , wherein said low melt base also contains enhancement agent.  
     
     
         50 ) The web of  claim 49 , wherein said enhancement agent is selected from the class of titanium dioxide, talc, silica, alum, calcium carbonate, calcium oxide, and magnesium oxide.  
     
     
         51 ) The web of  claim 49 , wherein said enhancement agent is present in a range from about 0.1 to 1.0 weight % of said low melt base.  
     
     
         52 ) The web of  claim 49 , wherein said bicomponent fiber has a high melting portion.  
     
     
         53 ) The web of  claim 52 , wherein said high melting portion is selected from the class of polyamides, polyesters, polyolefins, polyacrylates, and mixtures thereof.  
     
     
         54 ) The web of  claim 53 , wherein said high melting portion is polyester.  
     
     
         55 ) The web of  claim 53 , wherein said high melting portion is polyolefin.