Polyethylene protective yarn

Abstract

High strength polyethylene yarns useful in ballistic-resistant, cut-resistant and other applications, fabrics produced from these yarns and the methods by which the yarns and fabrics are made. An untwisted yarn of the invention comprises a plurality of filaments in essentially parallel array and from about 0.5 to 5 weight percent of a water-dispersible binder material covering less than half the surfaces of the filaments. The yarn has a tenacity greater than about 17 g/d, a tensile modulus greater than about 300 g/d, fewer than 20 entanglements/meter in a scoured state and a width less than given by the formula W≦0.055√{square root over (d)} where W is the yarn width in millimeters under a tensile load of 0.01 g/d measured on a flat surface and d is the yarn denier.

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       9 . In a process for the preparation of untwisted polyethylene yarns comprising a plurality of filaments in essentially parallel array, said yarn having a tenacity greater than about 17 g/d, a tensile modulus greater than about 300 g/d, and fewer than 20 entanglements/meter: the improvement comprising applying about 0.5 to 5 wt. % of a water-dispersible binder material so as to cover less than half the surfaces of the filaments during a last drawing step under a tension of greater than about 2 grams/denier.  
   
   
       10 . In a process for the preparation of a very low creep, ultra high modulus, low shrink, high tenacity multifilament polyethylene yarn by: 
 a) drawing a high molecular weight polyethylene yarn at a temperature within 10° C. of its melting temperature to form a drawn, highly oriented polyethylene yarn,    b) then poststretching said yarn at a drawing rate of less than about 1 second −1  at a temperature within 10° C. of its melting temperature, and cooling said yarn under tension sufficient to retain its highly oriented state;    the improvement comprising applying to the yarn about 0.5 to 5 weight percent of a water-dispersible binder material so as to cover less than half the surfaces of the filaments during one of drawing step a) or poststretching step b) under a tension greater than about 2 grams/denier.    
   
   
       11 . The process of  claim 9  wherein the water-dispersible binder material is a member selected from the group consisting of a salt of an acrylic copolymer, sodium carboxymethyl cellulose, polyethylene oxide, polypropylene oxide, ethylene oxide/propylene oxide copolymers, polyvinyl alcohol, modified starch, esterified starch, cationic starch, starch-styrene/butadiene copolymer, and mixtures thereof.  
   
   
       12 . The process of  claim 10  wherein the water-dispersible binder material is a member selected from the group consisting of a salt of an acrylic copolymer, sodium carboxymethyl cellulose, polyethylene oxide, polypropylene oxide, ethylene oxide/propylene oxide copolymers, polyvinyl alcohol, modified starch, esterified starch, cationic starch, starch-styrene/butadiene copolymer, and mixtures thereof.  
   
   
       13 . A process for the preparation of a ballistic-resistant fabric comprising the steps of: 
 a) weaving a fabric comprising in majority portion the yarn described by  claim 1;  and    b) flattening and spreading the yarns in said fabric by additionally applying one or both steps selected from the group consisting of scouring said fabric and calendering said fabric.    
   
   
       14 . The process of  claim 13  wherein said flattening and spreading step comprises scouring said fabric.  
   
   
       15 . The process of  claim 13  wherein said flattening and spreading step comprises calendering said fabric.