False-twist texturing yarn of polyester filaments having multilobal cross sections

Abstract

Multifilament polyester yarn, of multilobal filaments having specified cross-sectional characteristics, is false-twist textured into yarn which provides fabrics having improved visual aesthetics. The examples illustrate that freedom from objectionable glitter is obtained with 6 to 10-lobed filaments, having essentially symmetric lobes of equal length equispaced around a central axis of the filament, when the modification ratio is from 1.17 to 1.85, and the denier per filament is between 3.8 and a maximum value which is a function of the modification ratio and the number of lobes.

I claim: 
     
       1. An improvement in multifilament polyester yarn for false-twist texturing .[.at a maximum ratio (R) of output-to-input of up to 6:1,.]. wherein the improvement comprises yarn composed of polyester filaments of multilobal cross-section characterized by a total number (N) of 6 to 10 essentially symmetric lobes of substantially equal length, equispaced radially about the center of the filament, and having between 1.17 and 1.85 modification ratio (M), the filaments having a denier per filament between 3.8.[.(R).]. and (5.88M - 10 + N).[.(R)..]. at M = 1.85. 
     
     
       2. Yarn as defined in claim 1 wherein said polyester is polyethylene terephthalate. 
     
     
       3. Yarn as defined in claim 1 wherein said polyester is an ethylene terephthalate copolyester containing about .Badd.2 mole percent of 5-sodium-sulfo-isophthalate units in the polymer chain. 
     
     
       4. Yarn as defined in claim 1 wherein said polyester filaments have octalobal cross-sections. 
     
     
       5. Yarn as defined in claim 1 wherein said polyester filaments have positive lobe angles. 
     
     
       6. A false-twist textured yarn product of the polyester yarn defined in claim 1, wherein less than 12 percent of the filaments have a flattened cross-sectional periphery of greater than 10 microns and the filaments have a denier per filament between 3.8 and 5.88M - 10 + N.[...]. .Iadd.at M = 1.85. .Iaddend. 
     
     
       7. Polyester yarn as defined in claim 6 wherein said polyester is an ethylene terephthalate polymer. 
     
     
       8. Polyester yarn as defined in claim 6 wherein said polyester is an ethylene terephthalate copolyester containing about 2 mole percent of 5-sodium-sulfo-isophthalate units in the polymer chain. .Iadd. 9. Yarn as defined in claim 1, wherein the yarn contains a finish which provides it with a friction coefficient of less than 0.3 at the texturing temperature..Iaddend..Iadd. 10. Yarn as defined in claim 9 wherein the finish is 0.8-1.4 percent by weight of the yarn of (A) isocetyl stearate, sodium di(2-ethylhexyl)-sulfosuccinate, condensation product of 1 mole stearyl alcohol with 3 moles of ethylene oxide, triethanolamine and oleic acid or (B) coconut oil, sulfated glyceryl trioleate, glyceryl monooleate, condensation product of 1 mole nonyl phenol with 5-6 moles of ethylene oxide, oleic acid and triethanolamine.