COPOLYESTER AND HEAT BONDABLE FIBER

摘要

PROBLEM TO BE SOLVED: To obtain a heat bondable fiber which can provide a nonwoven fabric having excellent low-temperature heat bonding properties to a polyester fiber including polyethylene terephthalate and an excellent hue. SOLUTION: This heat bondable fiber comprises a copolyester as a heat- bonding component which contains 2-10 mmol% calculated as titanium metal element of a titanium compound soluble in a polymer based on the total dicarboxylic acid components, and composed of 50-80 mol% of an ethylene terephthalate unit and 20-50 mol% of an ethylene isophthalate unit in the components constituting the polyester, satisfies the formula (1): 2<=P/Ti<=15 and/or formula (2): 10<=Ti+P<=100 (Ti is the concentration (mmol%) of the titanium metal element of the polyester-soluble titanium compound contained in the polyester; P is the concentration (mmol%) of phosphorus element of a phosphorus compound contained in the polyester) and has 0.35-0.64 intrinsic viscosity.