Bicomponent binder fibers

Abstract

A bicomponent fiber comprising a first component and a second component is currently disclosed. The first component is comprised of from 70 to 97.5 wt. %, based on the weight of the first component, a polyethylene having a melt index, and from 2.5 to 30 wt. %, based on the weight of the first component, of a maleic-anhydride-grafted polyethylene having a maleic-anhydride level of from 0.50 to 3.00 wt. %, based on the weight of the maleic-anhydride-grafted polyethylene, and a melt index. The ratio of the melt index of the polyethylene to the melt index of the maleic-anhydride-grafted polyethylene is less than 1.25. The first and second components can be part of a core sheath, an eccentric core sheath, an islands in the sea, a side by side, or a segmented-pie structure. The disclosed bicomponent fibers can be used to produce nonwoven materials. These bicomponent fibers can produce nonwovens with improved bonding efficiency and better mechanical strength due to increased surface concentration of maleic anhydride as evidenced by a higher surface oxygen concentration.

1 . A bicomponent fiber comprising:
 a. a first component comprising:
 i. from 70 to 97.5 wt. %, based on the weight of the first component, of a polyethylene having a melt index, and 
 ii. from 2.5 to 30 wt. %, based on the weight of the first component, of a maleic-anhydride-grafted polyethylene having a maleic-anhydride level of from 0.50 to 3.00 wt. %, based on the weight of the maleic-anhydride-grafted polyethylene, and a melt index, 
   wherein the ratio of the melt index of the polyethylene to the melt index of the maleic-anhydride-grafted polyethylene is less than 1.25, and   b. a second component.   
     
     
         2 . The bicomponent fiber of  claim 1 , wherein the first component is a sheath component, and the second component is a core component. 
     
     
         3 . The biocomponent fiber of  claim 1 , wherein the bicomponent fiber comprises between 10 to 90 wt. % of the first component and between 90 to 10 wt. % of the second component, based on the weight of the bicomponent fiber. 
     
     
         4 . The bicomponent fiber of  claim 1 , wherein the second component comprises polypropylene, polyethylene, or polyester. 
     
     
         5 . The bicomponent fiber of  claim 1 , wherein the ratio of the melt index of the polyethylene to the melt index of the maleic-anhydride-grafted polyethylene is from 0.025 to less than 1.25. 
     
     
         6 . The bicomponent fiber of  claim 1 , wherein the polyethylene in the first component has a density of from 0.920 to 0.975 g/cm 3  and the melt index of the polyethylene in the first component is from 10 to 50 g/10 min. 
     
     
         7 . The bicomponent fiber of  claim 1 , wherein the melt index of the maleic-anhydride-grafted polyethylene in the first component is greater than 25 g/10 min and the maleic-anhydride-grafted polyethylene has a density from 0.856 to 0.965 g/cm 3 . 
     
     
         8 . A nonwoven comprising:
 a. 30 to 70 wt. %, based on the weight of the nonwoven, of the biocomponent fiber of  any preceding claim , and   b. 30 to 70 wt. %, based on the weight of the nonwoven, cellulose fiber.