PURPOSE: To enhance the printing life of the whole of a ribbon while enhancing the durability of a bonded part by using polyamide multifilament type yarns with sulfuric acid-relative viscosity of 2.4 or more and the difference in relative viscosity of 0.2 or more in a mixed state.

CONSTITUTION: Since yarn composed of a high viscosity polyamide polymer becomes hardly soluble in proportion to an increase in mol.wt., difference is generated in the melting degree at the time of ultrasonic welding due to the difference in viscosity. One of warp and weft yarns is constituted of a low viscosity polymer to ensure the adhesiveness of bonded parts and the other one of them is constituted of a highly viscous polymer to hold the shape of a fiber even after bonding. As the polyamide polymers being the raw materials of the warp and weft yarns, ones different by 0.2 or more in relative viscosity (ηγ) measured at 25°C using a 0.1% solution of a polymer in sulfuric acid with a concn. of 95.5% are used. By constituting the polyamide polymers being the raw materials of polyamide multifilament yarn of highly viscous nylon 66 with ηγof 2.7-3.2 and less viscous nylon 66 with ηγ of 2.4-2.6, the durability of a bonded part and the min. physical properties of base cloth for a ribbon are ensured.