Synthetic filament having a cross-section based upon an ellipse

Abstract

The present invention encompasses a filament having a cross-section based upon an ellipse where one side of the filament is defined by a convex-concave-convex curve. The invention also encompasses a spinneret and method for making the filament. The filament is preferably made from condensation polymers and in particular polyethylene terephthalate or other polyesters.

That which is claimed is:  
     
         1 . A synthetic filament having a cross-section, said filament comprising: 
 a primary axis and a secondary axis of different lengths,    wherein said secondary axis bisects said primary axis,    wherein said primary axis cuts said secondary axis into a first segment and a second segment where said first and second segments are of unequal length,    wherein said primary axis defines first and second portions of said filament cross-section on opposite sides of said primary axis,    wherein said first portion of said filament cross-section defines half of an ellipse,    wherein said second portion of said filament cross-section is defined by a curve extending between the ends of said primary axis and having first and second sections convex to said primary axis separated by a section that is concave to said primary axis with the trough of the concave section being defined by the end of the shorter of the two secondary axis segments.    
     
     
         2 . A filament according to  claim 1  wherein said filament comprises a condensation polymer.  
     
     
         3 . A filament according to  claim 1  wherein said filament comprises a polymer selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, poly(trimethylene terephthalate), other polyesters, polylactic acid, nylon 6 and nylon 66.  
     
     
         4 . A filament according to  claim 1  wherein said filament comprises polyethylene terephthalate.  
     
     
         5 . A filament according to  claim 4  wherein said filament further comprises polyethylene glycol.  
     
     
         6 . A filament according to  claim 5  wherein the weight fraction of said polyethylene glycol in said polymer filament is between about 2 percent and 20 percent.  
     
     
         7 . A fiber cut from the filament according to  claim 1 .  
     
     
         8 . A yarn comprising the fiber of  claim 7 .  
     
     
         9 . A yarn according to  claim 8  wherein said yarn is a blended yarn further comprising at least one other fiber selected from the group consisting of cotton fibers, rayon fibers, acetate fibers, polypropylene fibers, nylon fibers, spandex fibers, cellulosic fibers, biconstituent fibers, polylactic acid, and conventional polyester fibers.  
     
     
         10 . A fabric comprising fiber according to  claim 7  wherein said fabric is selected from the group consisting of woven, non-woven and knitted fabrics.  
     
     
         11 . A fabric comprising the yarn according to  claim 9  wherein said fabric is selected from the group consisting of woven, non-woven and knitted fabrics.  
     
     
         12 . A filament according to  claim 1  that is greater than 1 denier.  
     
     
         13 . A filament according to  claim 1  that is 1 denier or less.  
     
     
         14 . A spinneret for spinning a synthetic filament, said spinneret having at least one opening, said opening based upon an ellipse having a primary to secondary axes ratio of between about 1.8 to about 2.9, said opening further defined by a perimeter having a v-shaped notch generally (axially) aligned with said secondary axis and extending toward the center of the ellipse.  
     
     
         15 . A spinneret according to  claim 14  where in the origin of said v-shaped notch is located along the secondary axis.  
     
     
         16 . A spinneret according to  claim 15  where in the origin of said v-shaped notch is between the outer perimeter of said ellipse and the intersection of said primary and secondary axes.  
     
     
         17 . A spinneret according to  claim 15  wherein said origin of said v-shaped notch is at the intersection of said primary and secondary axes.  
     
     
         18 . A spinneret according to  claim 14  wherein said angle of said v-shaped notch is between 35° and 150°.  
     
     
         19 . A spinneret according to  claim 14  wherein said primary axis is between about 0.3 mm and 0.45 mm in length.  
     
     
         20 . A spinneret according to  claim 14  wherein said secondary axis is between about 0.13 mm and about 0.22 mm in length.  
     
     
         21 . A method of forming a synthetic filament comprising: 
 heating a fiber-forming material at or above its melting point;    spinning the heated material through a spinneret having at least one opening, the opening based upon an ellipse having a primary to secondary axis ratio of between about 1.8 to about 2.9, the opening further defined by a perimeter having a v-shaped notch generally axially aligned with said secondary axis wherein the angle of said notch is between 35° and 150°; and    spinning the heated material to form a filament.    
     
     
         22 . A method according to  claim 21  wherein the fiber forming material is a condensation polymer.  
     
     
         23 . A method according to  claim 22  wherein the condensation polymer is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, poly(trimethylene terephthalate), polylactic acid, other polyesters, nylon 6 and nylon 66.  
     
     
         24 . A method according to  claim 22  wherein the condensation polymer comprises polyethylene terephthalate.  
     
     
         25 . A method according to  claim 24  wherein the condensation polymer further comprises polyethylene glycol and a branching agent.  
     
     
         26 . A method according to  claim 25  wherein the concentration of polyethylene glycol in the melt is between 2% and 20%.  
     
     
         27 . A method according to  claim 21  wherein the filament is greater than 1 denier as spun.  
     
     
         28 . A method according to  claim 21  wherein the filament is 1 denier or less as spun.  
     
     
         29 . A method according to  claim 21  further comprising drawing the filament.  
     
     
         30 . A method according to  claim 21  further comprising cutting the filament into staple fiber.  
     
     
         31 . A method according to  claim 30  further comprising forming a yarn comprising the staple fiber.  
     
     
         32 . A method according to  claim 31  further comprising forming a fabric comprising the staple fiber wherein said fabric is selected from the group consisting of woven, non-woven and knitted fabrics.  
     
     
         33 . A synthetic filament with a non-circular cross-section that exhibits favorable properties in fibers, yarns and fabrics, said filament comprising; 
 a cross section comprising an ellipse with one portion that is concave with respect to the primary axis of the ellipse; and    said concave portion being symmetrical about the secondary axis of the ellipse.    
     
     
         34 . A synthetic filament according to  claim 33  wherein said filament comprises a condensation polymer.  
     
     
         35 . A synthetic filament according to  claim 33  wherein said filament comprises a polymer selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, poly(trimethylene terephthalate), polylactic acid, other polyesters, nylon 6 and nylon 66.  
     
     
         36 . A filament according to  claim 33  wherein said filament comprises polyethylene terephthalate.  
     
     
         37 . A filament according to  claim 36  wherein said filament further comprises polyethylene glycol.  
     
     
         38 . A filament according to  claim 37  wherein the weight fraction of said polyethylene glycol in said polymer filament is between about 2 percent and 20 percent.  
     
     
         39 . A fiber cut from the filament according to  claim 33 .  
     
     
         40 . A yarn comprising the fiber of  claim 39 .  
     
     
         41 . A yarn according to  claim 40  wherein said yarn is a blended yarn further comprising at least one other fiber selected from the group consisting of cotton fibers, rayon fibers, acetate fibers, polypropylene fibers, nylon fibers, spandex fibers, cellulosic fibers, biconstituent fibers, polylactic acid, and conventional polyester fibers.  
     
     
         42 . A fabric comprising fiber according to  claim 39  wherein said fabric is selected from the group consisting of woven, non-woven and knitted fabrics.  
     
     
         43 . A fabric comprising the yarn according to  claim 41  wherein said fabric is selected from the group consisting of woven, non-woven and knitted fabrics.  
     
     
         44 . A filament according to  claim 33  that is greater than 1 denier.  
     
     
         45 . A filament according to  claim 33  that is 1 denier or less.