GB997801A - Improved ribbons and methods of making same - Google Patents

Abstract

A ribbon for carrying ink in a printing device is made by weaving into a fabric a synthetic multifilament stretch yarn, which has been prepared by false twisting and heat setting in the twisted condition, and treating the woven fabric so that it becomes uniformly puckered. After false twisting and heating, the yarn is subsequently heat annealed by dry heating at 325-460 DEG F. for 0.2 to 1.5 seconds. Preferably both the warp and weft contain this stretch yarn but a conventional non-stretch synthetic thermoplastic, multifilament yarn may be used as the warp. Nylon yarn and/or polyethylene terephthalate yarn may be used. During weaving, the stretch yarn is kept under sufficient tension to stretch the yarn to its maximum length usually 200% to 300% of its relaxed length. After weaving, the fabric is removed from the loom and exposed in a fully relaxed condition to water containing 0.1% by weight of detergent, e.g. an alkylaryl polyether alcohol surfactant, and a neutralizing agent, e.g. sodium carbonate, at 175-200 DEG F. for 15-45 minutes resulting in the puckering of the fabric, shrinkage being in the order of 10-30% of the original width and length of the fabric. The fabric is frame dried at 220-235 DEG F. under tension at predetermined width and is then exposed to dry heat, e.g. at 350-400 DEG F., and held at the proper width to set the fabric. The fabric is cut into ribbon form and conventionally inked. In the examples, a twisted stretch nylon yarn is prepared by false twisting on a machine using a spindle speed between 40,000 and 240,000 r.p.m. with an average speed of approximately 150,000 r.p.m. at the rate of 95 to 130 turns per inch with an average of 121 turns per inch while heating the twisted yarn in a temperature range from 350-440 DEG F. and at rate of 25-50 yards per minute to give an exposure time of 0.2-1.5 seconds after which the heat set yarn is subsequently annealed in a temperature of 325-460 DEG F. for approximately the same length of time. During this latter process the yarn is overfed into the twisting unit at a rate varying from 0.2 to 18% in a rate range of 15-117 yards per minute. Polyacrylic acid may be applied to the yarn to facilitate weaving. Specification 902,330 is referred to.