| 摘要 |
PURPOSE: A manufacturing method of polyethylene-2,6-naphthalate fiber having high tenacity, high tensile strength and excellent workability is characterized by adding silica in melt-polymerizing to give excellent spinning property and reducing yarn-cutting. A treated cord manufactured out of the polyethylene-2,6-naphthalate fiber is useful for reinforcement for rubber products like a tire and a belt. CONSTITUTION: Polyethylene-2,6-naphthalate fiber is obtained by the steps of: (A) preparing solid state polymerized polyethylene-2,6-naphthalate chip containing at least 85mol% of ethylene-2,6-naphthalate unit and having 0.70-1.20 of inherent viscosity; melt-spinning the polyethylene-2,6-naphthalate chip to manufacture melt spun yarn; (B) passing the melt spun yarn through a delay-cooling area and a cooling area to solidify the melt spun yarn; (C) winding the yarn at proper spinning velocity to make undrawn yarn having 0.001-0.1 of birefringence; and then (D) multistage-drawing the yarn at 50-250deg.C in a total draw ratio of at least 1.5. The polyethylene-2,6-naphthalate fiber has (1)0.6-1.10 of inherent viscosity, (2)8.0-11g/d of strength, (3)6.0-15% of elongation, (4)at least 0.35 of birefringence, (5)1.355-1.368 of density, (6)267-280deg.C of melting point and (7) 1-5% of shrinking percentage. |
