DETAILED DESCRIPTION OF THE INVENTION The feed yarns of the present invention consist essentially of synthetic linear ethylene terephthalate polyester multi-filaments.
The term "synthetic linear ethylene terephthalate polyester" means a substantially linear polyester containing at least 85 mole percent, preferably at least 95 mole percent, of ethylene terephthalate units.
The preferred polyester is a polyethylene terephthalate, but copolyesters containing less than 15 mole percent of other copolymerizable components may also be used.
Examples of other acid components to be copolymerized with ethylene terephthalate include dibasic acids such as phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, adipic acid, oxalic acid, sebacic acid or suberic acid.
Examples of other alcohol components that can be copolymerized with ethylene terephthalate are dihydric alcohols such as polymethylene glycols having 2 to 10 carbon atoms (trimethylene glycol and butylene glycol, for example) and cyclohexane dimethanol.
The polyester may contain a minor amount of a modifier such as 5-oxydimethyl isophthalate, 5-oxydimethyl hexahydroisophthalate, benzene-1,3,5-tricarboxylic acid, para-carbomethoxyphenyl diethyl phosphonate, 3,5-dicarboxy phenyl diethyl phosphate, pentaerythritol, glycol, phosphoric acid, triphenyl phosphate, tri-1-carbomethoxyphenyl phosphate, triphenyl arsenite, tricapryl boric acid, sorbitan, trimesic acid or diethylene glycol.
The polyester may also contain minor amounts of the usual additives, such as delustrants, antistats, antioxidants, pigments, dyestufffs and fireproofing agents.
The feed yarn useful in the present invention consists essentially of the polyester above-mentioned having an intrinsic viscosity of 0.
3 - 1.
0.
The feed yarn according to this invention should be an undrawn yarn obtained by the modified melt-spinning process and having such properties as follows: a.
Break elongation (El.
) of 40 - 80%, preferably 50 - 75%, and more preferably of 60 - 70%.
b.
Density (
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Manufacturing Materials 
