Trilobal yarns for application on dental floss, dental floss including the same and use of triloba yarns in the manufacture of dental floss

Abstract

The present invention refers to yarns made of hollow trilobal cross section filaments, comprising from 90 to 99% of polypropylene, and between 1 and 10% of other polyolefin resins, for the application on dental floss. This invention additionally refers to the production process of the yarns made of hollow trilobal cross section filaments. This invention additionally refers to dental floss comprising hollow trilobal cross section filaments, and the use of hollow trilobal cross section filaments for the manufacture of dental floss. The yarn described in this invention has linear density or title in the range from 400 to 1200 dtex, and it is twisted with a twist level from 10 to 160 twists per meter.

1 . A yarn comprising filaments with hollow trilobal cross section, characterized by comprising from 90 to 99% polypropylene and between 1 and 10% of other polyolefin resins, for the application on dental floss. 
     
     
         2 . The yarn according the  claim 1 , characterized by comprising 95% polypropylene and 5% polyolefin resin. 
     
     
         3 . The yarn according to  claim 1 , characterized in that the polyolefin resin is polyethylene. 
     
     
         4 . The yarn according to  claim 1 , further comprising additives chosen between dyestuffs and pigments. 
     
     
         5 . The yarn according to  claim 1 , wherein the yarn has a linear density or title in the range from 400 to 1200 dtex, and the yarn is twisted with a twist level between 10 and 160 twists per meter. 
     
     
         6 . Dental floss comprising a hollow trilobal cross section filament comprising 90% to 99% polypropylene and between 1% and 10% other polyolefin resins. 
     
     
         7 . (canceled) 
     
     
         8 . A method of making the yarn of  claim 1  by multifilament melt spinning using synthetic resin as raw material, comprising:
 feeding raw material to an extrusion melt spinning machine, wherein the raw material is polypropylene pellets, and the extrusion melt spinning machine comprises an extruder, gear metering pumps, spinnerets, quench cabinets, spin finish applicators, draw rollers, tangling nozzles, and a winding system; 
 melting the polypropylene pellets in the extruder with the addition of a pigment masterbatch to obtain a molten mass, wherein the pigment masterbatch comprises the other polyolefin resin; 
 pumping the molten mass throughout the spinnerets, to generate a product in form of continuous hot molten filament yarn; 
 cooling the hot molten filament yarn with air to turn it solid, and subsequently lubricating, drawing, and tangling the cooled filament yarn with air, and finally winding the cooled filament yarn onto paper tubes; and 
 twisting the yarn with 10 to 160 twists per meter.